Cast Marble

I actually got Hanayama's Cast Marble about a year ago and forgot to write my review of it. Oh well! Better late than never!

It was designed by Bram Cohen and Oskar van Deventer. It has a very interesting appearance, with a silver marble embedded in an obsidian-colored block. The marble protrudes from both sides slightly, and both pieces have unusually shaped cuts in them.

Despite the fact that I had a pretty good idea of how this one should work, I think it took me a good 10 minutes to actually get it to come apart. I think most will find this to be quite challenging, so the 4/6 difficulty rating seems appropriate. It is difficult because there is some movement that is not related to the solution and the actual solution is an unusual movement. Also, things need to be positioned precisely, which makes it difficult too.

Some folks on the Puzzle Master reviews report difficulty putting it back together, particularly if you didn't see and understand how it came apart. This wasn't a problem for me, but I could definitely see it tripping folks up.

The puzzle has a great weight since it is solid metal. The only downside I think is that the black coating they used picks up finger prints like nobody's business. Not a huge problem of course, but it is the only thing I noticed. Overall, it is a great puzzle that'd recommend trying out.

Well, that's the last post of 2010: I hope everybody has a happy new year! Stay tuned in 2011 for lots more reviews, including the 2010 Karakuri Club Christmas presents and a new box by Robert Yarger!

Bits and Pieces Puzzle Boxes (Part 4)

I ordered this next batch of Bits and Pieces puzzle boxes during a sale they were having this month. Even though the puzzles can be a bit hit-or-miss (see part 1, part 2, and part 3), I'm always curious enough to keep buying them. Sometimes you can stumble across a real gem at a good price.

Of this order, I think Secret Drawer Box is my favorite. Bits and Pieces does not say who designed it in the description, which is a bit unusual. It has a nice appearance and a good finish. I tend to like the look of boxes with drawers, and the dark wood knob is cute.

The solution to Secret Drawer Box is not too tricky to find, but could take a few minutes or more. I think it only took me a minute or so, but it could take longer. The solution is fairly unique, but related in some ways to another box I have seen, which is likely why it didn't take me long to solve.

One downside to this puzzle is that you may accidentally open the box without knowing what you did! In that case, you'll find yourself unable to lock it, so now you have a new puzzle to deal with. This isn't a big problem as long as you are aware that this might happen. Definitely a good buy at $15, and it is on sale for $12 currently!

Confidential Keeper is another one that I liked. It is also just listed as 'exclusively designed for us', so I'm not sure who the designer is. The appearance of this one is also fairly good, with inlaid stripes going around the outside of the box. The first move is not well disguised in my version of the box, though it looks much better in the photo, so there is likely some variation.

Despite the first move being poorly hidden, the second move is quite well disguised! I think it took me a good 5-10 minutes to find the solution to this one. It required a bit more force than I would have liked the first time, but after that it loosened up a bit. I showed this to some non-puzzler friends and they also enjoyed it and most were able to solve it after a few minutes. At $15, I think this would also be a good one to pick up while it is available.

Two for two! Unfortunately the next one, Secret Sliding Box by Alan Boardman, was a bit of a dud. The first move is the same as Confidential Keeper (though better disguised), and that is all there is to it! That wouldn't be too bad, but that single move requires a lot of force, though I'm sure there is some variation across individual copies of this box.

On top of that, the hinge in the back is weak, so when I showed this box to some friends, they found that they could unlock the box simply by twisting the lid due to the loose hinge. They thought that this was the solution, which would be somewhat clever I suppose, but it will likely damage the box if done repeatedly. Don't bother with this one!

We continue to Original Kamei Telescoping Square Box, which has a really cool name. I was envisioning some interesting nested telescoping mechanism or something like that. The appearance of this one is not bad, it has light wood inlays in the corner which is a nice touch. I also like the rounding on the top. The base of the box is the same as Karakuri Small Box #4, #5, and #6, if you are familiar with those.

I worked on this one for a good 10-15 minutes before I started to think that I may have gotten a bad box. Fortunately, Kellian was there and was able to take a look at the solution. She said that she was surprised that I hadn't tried the solution already, and indeed it turned out to be something that I had tried! The box wasn't working properly.

Since I knew how the mechanism should work, I was able to devise a way to open it (using improvised tools) despite the fact that it wasn't working correctly. Unfortunately, this wasn't a long-term solution. I'm planning to let Bits and Pieces know that this box didn't work, and they'll probably issue some kind of credit on my account. They tend to be pretty good about these things, which makes the bad quality control somewhat more tolerable.

The actual solution is pretty good, though I'd recommend getting Karakuri Small Box #6 instead. The storage space is smaller, but the quality is way better.

That brings us to the final box of this batch, The Double Octagon Puzzle Box by Jean Claude Constantin. Unlike most puzzle boxes where the challenge is to open the box, the challenge of this one is to put it back together once you've opened it.

The metal screw on the top unscrews, the top lifts off, and the eight side panels fall out of place. Now your task is to put them back! Each plate has two tabs on each end, each of which can be skinny or fat. The lid and the base have holes in them with either tab fitting in the large hole and the small tabs fitting in the small holes.

The appearance of the box is OK, but not as good as other Bits and Pieces boxes. It is clearly laser cut and the finish is a bit rough, particularly on the side panels.

As a puzzle, I found it to be pretty good. You would think that it would be a lot of trial and error, but I was able to make some deductions based on the pieces that were available that sped up my search significantly. I think most will find this to be fairly difficult. It took me about 10-15 minutes to get it back together. Overall, not bad, but not really a standard puzzle box. If you like assembly puzzles like this, then I would recommend it.

In all, I was happy with the boxes I got in this order. I had a good time solving these boxes and will keep an eye out for more in the future.

Bits and Pieces Puzzle Boxes (Part 3)

I actually purchased this set of puzzle boxes from Bits and Pieces way back in January but never got around to writing about them! I recently got a few more and was getting ready to write about them, but figured I should write about the older ones first. Check out my first and second post about other Bits and Pieces puzzle boxes.

My favorite of this batch was The Elegant Kamei Ribbon Box, shown here. As you can see, the appearance of this one is quite striking. The bow on the top looks nice, as do the splines on the sides.

Fortunately, on top of looking nice, it is actually a pretty good puzzle. It is a reproduction of a design by Akio Kamei of the Karakuri Creation Group, and there are two interesting tricks that Kamei included here. I don't want to spoil it by going into any more detail.

The actual solution is the same as Karakuri Small Box #4, though the appearance is different and the tricks I mentioned previously are not present, which makes it somewhat easier.

This is one of the more difficult puzzle boxes that Bits and Pieces is currently selling, from what I have seen. Definitely worth checking out if you don't have a copy of the real thing! Due to its complexity, it is a bit more expensive than some of their other boxes at $30 currently, but I think it is worth it since the quality is quite good.

This next box is The Elegant Kamei Heart Box, which requires multiple steps to open. As you can tell from the name, it is also designed by Akio Kamei. It looks pretty good in this photo, but the red dot in the middle of the bow is painted, which I don't think looks very good since it isn't painted evenly.

When I tried to solve this one, I got stuck pretty quickly, though I felt like I knew what needed to be done. I checked the solution and confirmed my suspicion that the box was jammed! Fortunately, I was able to free it by applying a bit of extra force. The wood used for the mechanism is not smooth at all, which can cause problems if splinters get caught up in the mechanism.

Another big problem with this box is that the drawer is not spring loaded, but the interior is not smooth enough for it to slide out on its own with gravity. Because of this, I needed to dig my fingernails in to pull the drawer out. They really should provide some kind of drawer pull or smooth things out more. This is probably not a problem for every copy of this box, but something to be aware of. I found this really annoying, and wouldn't recommend buying this one. The solution is pretty simple, but what makes it difficult are the design/construction flaws I mentioned, which is not a good thing!

Next up is Oval Trick Box, which was designed by Jean Claude Constantin. It has an interesting shape, with the dark wood on the lid and base contrasted by the side panels.

I solved this one almost immediately, as did some friends that I showed it to. It is a fairly simple solution, but the implementation of the actual mechanism is a bit unusual. However, this mechanism also makes for a pretty small opening for storing things in the box.

Due to its simplicity, I would say that this box would be good for younger children, but more seasoned puzzlers will probably be a bit bored by it. Still, the price is not bad at $15!

Finally, we have Shut Case Box (a.k.a. Cam Box), which is a design by Eric Fuller. Unfortunately, it is not currently for sale at Bits and Pieces, though I feel like I saw it there a few weeks ago. The photo is by Jeff of MagicPuzzles.org: check out his entry about Shut Case Box.

This is an interesting variation on the usual sliding panel design, with the end panels inset as shown in the photo (the other end looks the same). I'm not really sure of the reason for the original name, as there doesn't appear to me a cam involved, though I'm sure there is some explanation.

I'm sure it varies somewhat, but in my version one of the end panels is slightly too large. This doesn't seem to be a problem when opening the box, but makes it a bit difficult to close. Bits and Pieces is quite good about sending you another copy if your box isn't working right, but I usually don't bother unless it is really bad. If you have a chance to pick up a copy of this puzzle, I think it would be worth doing so, since it is quite reasonably priced. Just hope that your copy works well! In Jeff's entry, it sounded like his worked fine, so it does vary somewhat.

In all, I was moderately happy with this batch of boxes. The prices are so low that you can't really gripe too much if they're not perfect, and you sometimes find a real gem like the Ribbon Box. Stay tuned for another batch of boxes that I purchased this month!

Perplexus

For Christmas, one of the puzzles I received from my parents was this cool 3D maze puzzle called Perplexus. (Thanks Mom and Dad!) Unlike most of the puzzles that I have where the goal is to either take it apart or put it together, this is a dexterity puzzle where the goal is to navigate a ball through an obstacle course.

Just reading that description doesn't sound all that interesting, but as you can see from the photo, the obstacle course is very elaborate! There are 100 different 'barriers' to overcome to reach the end, so it is quite a challenge. I'm saying obstacle course rather than maze since there aren't really any dead ends, it is a linear path. Here's a catchy promotional video from the Perplexus website that shows the puzzle in action:



The puzzle has a long story behind it: the concept was originally created in the late 1970's by Michael McGinnis, a 3D design teacher, who envisioned adapting his idea into a toy. 20 years later, Michael collaborated with Brian Clemens and Dan Klitsner of KID Group, a toy inventing group, to make the idea suitable for consumers. It was launched as Superplexus by Hasbro  in 2001 with an electronic timer and sound effects.

Recently, it was re-released by PlaSmart as Perplexus with no electronics, which is the version I have. No batteries to change! There are knock-offs for sale under the names Magical Intellect Ball, 3D Labyrinth IQ Puzzle, and Addictaball, but you should buy the licensed version to support the inventor. Check out a full article on Michael and the Perplexus by the San Francisco Chronicle with some photos of Michael and his first sketches of the puzzle.

Michael created a massive version of this puzzle that is currently for sale at Hammacher Schlemmer for $30,000. Pretty amazing! Considering how much that toy cost, I would think the kid in the picture would be more excited. I wonder how manipulating this massive version compares to the smaller handheld version. Here's a video of another giant Superplexus that Micheal created in action. Check out SuperPlexus.com for more photos about the construction and history of this puzzle.

Back to the Perplexus: the puzzle has three starting points numbered 1, 2, and 3 that will start you at barrier 1, barrier 28, or barrier 59. This is quite handy because it is extremely difficult to solve the entire puzzle in one go. I've been working on it for the past two days and haven't had much luck. It took me about an hour to get all the way through it even using these 'save points' once I had made it past each one. Pretty challenging!

That said, the first third of the course in actually fairly easy. There are pretty high walls on either side of the path, so it is just a matter of navigating the ball in the correct direction. After the 2nd starting point, it gets quite a bit more difficult and will challenge even the most dexterous puzzler!

We had family over for Christmas and my cousins really enjoyed this puzzle. They were taking turns trying to get the whole thing done throughout the afternoon.  It really draws you in since you want to see what will come up next after the point where you just fell off. It feels a bit like a Revomaze in that you keep getting further and further before you fall off, which encourages you to continue.

I think the only downside to this one is that it is damn frustrating, but that just makes it all the more sweet when you finally get past a tough part. Even though you may get frustrated, I think most will be tempted to return to it and try to finish it. Also, the construction is plastic, which some people may not like. I liked the colors, and it seemed quite durable, though I'm going to be careful about preventing scratches on the exterior.

Overall, Perplexus is an awesome puzzle! Compared to the standard dull dexterity puzzle with a few balls rolling around randomly in a small plastic case, this one blows them out of the water! It makes me wonder if there are any other interesting dexterity puzzles like this that I'm unaware of. Let me know in the comments if you know of any must-have dexterity puzzles that are out there.

Definitely check this one out! Even if it doesn't quite seem like it is up your alley and you usually don't like dexterity puzzles, I think pretty much anybody will enjoy it. They also make great gifts for kids of all ages (3+) as well as adults.

Solitaire Chess

This year, ThinkFun launched a new puzzle called Solitaire Chess, designed by Vesa Timonen. Tanya Thompson was kind enough to send me a copy for helping them test out another puzzle they are working on. Thanks Tanya!

The idea of Solitaire Chess is to set up the pieces as shown one of the challenge cards and, by capturing pieces with every move, end up with only a single piece remaining on the board. In this way, it is similar to the peg-solitaire game that became so widely known. The standard movements of the chess pieces apply. However, there are no black and white pieces, only blue, so there are no alternating turns like in regular chess. As such, you can repeatedly move the same piece.

There are sixty challenges on double-sided cards that are divided into four levels of difficulty. I thought that the challenges progressed quite well, and even the beginner ones were challenging at times. Some I was able to solve right off, but others took me a minute. As the difficulty increased, the challenges got quite hard!

When you get stuck, there is a great hint system that is provided in the instruction booklet. You can look up which piece moves first, which often times in just the nudge you need to get started. If you're still stuck, you can look to see which piece that first piece captures, which further helps you out. If that still doesn't narrow it down enough, you can also look up what the final piece on the board will be. Working backwards from there is quite helpful. Finally, if you give up completely, the solutions are provided.

This hint system was really good, though I'm always reluctant to use it. On a few of the more difficult challenges I found myself peeking at a hint when I was completely stumped as to where to begin. For the more difficult challenges, there are more pieces on the board so finding out where to start is quite challenging.

In all, I would say that the range of difficulty is quite good: the easy ones are a good introduction to the puzzle while the more difficult ones will really make you put your thinking cap on. Plus, with 15 puzzles at each of the four difficulty levels, there is plenty at your favorite level. The challenges kept me busy for a number of hours spread out over a couple of days.

The pieces stow away inside the base of the puzzle, which is great! I love a puzzle that is self contained like that. The cards stow in the top half of the compartment, though I had an issue with the cards being too big for the compartment. ThinkFun was quick to send me another batch of cards, but this set only fit in sideways which is mildly annoying. Tanya informed me that they're aware of the issue and are addressing it, so I wouldn't worry much about it. Only one of the five reviews on Amazon cited the issue, so it was probably just a problem in one batch.

Overall, Solitaire Chess is another great puzzle by ThinkFun that I really enjoyed! I think this one is sure to be a hit because it will draw in chess fans as well as puzzle people. I'm not sure if it will do anything for your chess game, but it is still good fun. Definitely check it out!

Cast Ring II

Cast Ring II is the last of the three Hanayama puzzles I tried out. I previously reviewed the predecessor Cast Ring, which I really had a good time with. Cast Ring II  was originally designed by Jose Grant, the world's foremost puzzle ring designer and craftsman who died recently. The design was modified by Nob Yoshigahara for Hanayama.

It differs from the original Cast Ring (shown to the left) in a number of ways: Cast Ring II has five bands rather than four, it has a 5/6 difficulty rating while the original was 4/6, the overall design is less curvy/woven with only two of the five rings curved. Because if this last point, it doesn't really stay together as well as the original. A slight bump will push the rings out of alignment, which I found annoying.

I pulled this one out of the package and scrambled it up, trying not to see how it came apart. Despite this, I was able to get it together in a minute or two. This was somewhat disappointing since the original cast ring had taken me closer to 45 minutes! I guess that was a while ago and I have more puzzle experience now, but I still think it is easier than the original. This was surprising since it has a higher difficulty rating.

I think the fact that there is an odd number of rings made it easier to figure out how to start. The bands on the outside just kind of flop around and pretty easy to figure out where to place. Bands 2 and 4 are a bit trickier, but not too bad.

Overall, I'd don't  recommend unless you're really into puzzle rings, and in that case you've probably got much better ones than this.. Definitely check out Cast Ring, but you can skip Cast Ring II.

On a separate topic: I'm getting married in June and am planning on getting a wedding band from Jose Grant's shop in Stamford Connecticut. Let me know if you have any advice or favorite designs in the comments! I think I'm leaning toward an odd number of bands, probably five or seven.

Cast Plate

After grabbing some pizza and solving Cast Bike, I hopped on the subway to make my way home. As I was waiting for the train, I pulled out Cast Plate and started to fiddle around with it a bit. It is an old design that has been adapted by Nob Yoshigahara for the Hanayama Cast Puzzles series.

It is a bit hard to tell from the photo, but the vertical bar at 12-o'clock is actually a ring with a gap in it. You rotate the ring until the gap is at one of the holes, and then can pivot the gap to a different hole. In this manner, you can navigate the ring to the gap in the ridge around the plate and get the ring off. Sort of complicated to explain, but pretty intuitive.

I got on the train and ended up sitting next to an older gentleman. We got to chatting about puzzles while I continued to work on this one. I offered him Cast Bike, but he wasn't interested in trying it out. I fiddled around with it for about 10-15 minutes, going around in circles quite a bit. It is really difficult to visually judge which holes can reach to which other holes, so you sort of need to memorize what you have tried. This is a bit tricky while trying to carry on a conversation, but finally was able to get the ring off!

I have since played around with it a few more times and can appreciate some of the cool ideas that Nob threw into this maze. For one thing, there is a little lump in the plate that obstructs your path just as you think you are about to reach the exit. I thought I was almost done, but in fact I was only about half way there. There are also a number of loops that make it easy for you to go around in a circle and end up going back the way you came. That said, I think it is correctly rated at 2 out of 6 difficulty level.

This is a fun puzzle I think anybody could enjoy. It sort of sucks you in because it is easy to fiddle around with and feel like you are making progress. One downside to this one is that the ring is a bit difficult to turn unless you have it lined up just right. The reviews on Puzzle Master indicate that it loosens up over time, but I haven't played with mine enough to notice this yet. Still, it isn't a huge problem and doesn't detract much from an otherwise solid puzzle.

Thanks to Puzzle Master for making this review possible!

Cast Bike

After my visit to Eureka, I went to grab some lunch. While I was waiting, I decided to start working on Cast Bike. I chose that one because I figured it would be somewhat easier that Cast Plate and Cast Ring II.

I thought that it would be easy because it is a level 1 out of 6 and from seeing pictures I knew the general idea of what I needed to do: there is a ring with a small gap in it that must be navigated to an exit point. The gap is thinner than the thickness of the bike, but there are channels on both side that allow it to move.

This puzzle was originally designed and patented by John R. Lynn back in 1898, but this replica was created by Nob Yoshigahara. Nob mentions in the description that they did not have a puzzle for reference, which made this a difficult task.

As with all of the Hanayama Cast puzzles, it is nicely made. This one is a bit flat, which makes it somewhat less appealing than some of the more interesting shapes. However, I think the fact that it is a bike draws people in, since it is a familiar object.

I think it took me a good five to ten minutes to solve this one, though I was eating pizza at the time. I think if I was just doing that it would have taken less than five minutes.

The solution is quite lengthy, with approximately 41 moves depending on how you count. However, there are not very many dead ends, and they tend to be pretty short. I had the most trouble in the wheels, there is an interesting trick that is used there that I didn't notice at first. I think most folks will be able to solve this one within ten minutes or so, it is the sort of thing that just takes a bit of time due to its length.

Overall, Cast Bike is another solid puzzle by Hanayama that I would recommend. Thanks to Puzzle Master for making this review possible!

Lovely Burr

As I mentioned in my last post about The Pentangle Puzzle, on Saturday I headed over to Eureka Puzzles and Games in Brookline. Puzzle Master had sent me four Hanayama puzzles to review, but I already had three of them: Cast H&H, Cast Vortex and Cast Marble (which it appears that I forgot to review). So I was hoping that David, the owner of Eureka, would be kind enough to trade me for some that I didn't have.

When I arrived, the store was jammed with holiday shoppers! I was glad to see that business was going so well, but didn't want to take up too much of David's time during the holiday rush. Despite being busy, he was nice enough to spend some time chatting and pointing out some of the new puzzles that I might be interested in.  That's one of the great things about this store, there are always plenty of folks who are happy to help customers out, so even when they are busy you feel like you get enough personal attention.

David told me that he had recently received a puzzle from Jerry McFarland named Lovely Eighteen-Piece Burr and handed it to me to try out. He told me that it was designed by Bruce Love of New Zealand in the 1980's and was crafted by Jerry. Jerry does some awesome work with burrs and has crafted many fine burr puzzles designed by Bill Cutler.

The layout of the burr is the standard 18-piece design, with six pieces in each axis. As such, you can't really tell by looking at it which design it is. The photo on the right shows an older run of this puzzle that Jerry had done. The version that I tried had three different colors of wood used, one for each axis, which makes it somewhat easier to re-assemble if you are foolhardy enough to attempt that. It takes 18 moves to remove the first piece, which is cute considering that it is an 18 piece burr.

I set myself to the task of trying to remove the first piece. I didn't want to disassemble it completely since I would need a lot of room to lay the pieces out so I didn't forget where they came from. Also, if I screwed up it could take many hours to get it back together. As it was, I had a hard enough time getting the first piece out!

This is a very tricky burr because there are frequently a number of moves possible at any point, only one of which is correct. This makes it very easy to get lost along the solution path and end up at a dead end. I think it took me about 25 minutes to get it apart and just as long to get it back. There was one piece in particular that I had trouble remembering how I moved in the first place, which was what took me so long to get it back to the start. This is definitely not one that you can easily muddle through to get it apart, you need to think about what you're doing.

The craftsmanship is very nice, as I've seen in all of Jerry's work. This particular copy was slightly loose, I prefer a burr that is tight enough so that the pieces do not slide accidentally by gravity. This is difficult to achieve and can vary with humidity, but most of Jerry's work that I have tried his property.

The solution itself is quite convoluted and has some pretty tricky moves. It is a great design by Bruce and I would definitely recommend it if you like burrs with a fairly moderate number of moves. I think Eureka only has one copy and it is currently not listed on their website, but if anyone is interested I'll bet they will sell it to you over the phone and ship it. I think that Jerry is planning to make more in 2011 too.

Even though it was enjoyable, I was quite relieved to finally get it back to where it started! I would have hated to leave it partially solved, that is poor puzzling form. After that, David was indeed kind enough to trade the three Hanayamas I mentioned earlier for three that I didn't have: Cast Bike, Cast Plate, and Cast Ring II. Reviews for these will be coming up soon!

As I was picking these out, there was a fellow who was examining Cast Baroq and couldn't resist telling him that it was my favorite in the series. I hoped that he knew something about puzzles so we could chat for a bit, but unfortunately he did not. He asked if I thought it would be a good difficulty for a 15-year-old, and I said yes and proceeded to describe why it is an awesome puzzle. He said that he was also shopping for an 11-year-old and a 12-year-old, so I recommended Cast Loop and Cast Key to him, since those are a bit easier but still quite good. He ended up purchasing all three. Hopefully the kids will enjoy them!

As I was getting ready to head out, I was glad to see Saul Bobroff and Tim Udall walk in, two mechanical puzzle collectors in the area with awesome collections. We talked about puzzles for a bit and what we were all purchasing. I don't recall what Saul got, but Tim bought Cast Helix (another one I've forgotten to write about) and Cast Rattle (which is very cool). I told him abut the fun I had with Chain Gang, so he ended up grabbing that one as well. After we made our purchases, we parted ways. It was great seeing them both! What a funny coincidence!

I headed over to get a piece of pizza at The Upper Crust and solve some of the puzzles I just got. I'll be writing about those in my next few posts.

The Pentangle Puzzle

About six months ago, Kellian and I visited the Higgins Armory Museum out in Worchester, Massachusetts. After touring the museum (which is quite cool), we stopped by the gift shop. As usual, I did a quick scan around for mechanical puzzles. Much to my delight, there was a series of tubes that contained disentanglement puzzles.

It was a bit hard to tell what they were due to the tubular packaging, so I just grabbed the most difficult one which was four out of four stars labeled 'Genius' and hoped that it was something I hadn't seen. It didn't actually have a name other than "Puzzle Drum Mindgame Collections" on the packaging. This was apparently so they could keep costs down by not printing different packaging for the four different puzzles in the series.

When I got it out of the package, I realized that I had seen the design before over at Livewire Puzzles, and it was named The Pentangle Puzzle. Since it is confusing to refer to the unnamed puzzle that I actually have, I'll be referring to it as Pentangle since that name feels appropriate. To the left is a photo of the Livewire version. It is a bit hard to tell that they are the same since the photo above isn't playing up the pentagonal aspect, but they are essentially the same. I loved Livewire's description:

If you research puzzles long enough, from time to time you'll stumble upon a real gem. Where this puzzle, which we call Pentangle, originated, is not known, but we should all take our hats off to the genius who came up with it.

In solving a puzzle, most adults draw from their experience, particularly experience obtained from solving other puzzles. Furthermore, we have found that the more education you have, the more you tend to draw on skills and problem-solving techniques learned in school to help solve a puzzle. Both types of experience can be helpful, but in some instances they may divert our attention away from the area where we should be focusing. Such experience actually hinders us more that it helps us.

Experience is often powerless when faced with a lateral-thinking puzzle. Lateral-thinking puzzles are perhaps best described as puzzles in which conventional thinking breaks down. Solving such a puzzle requires a change of perspective, and the more set in your ways you are, the more difficult you will find such a puzzle.

We have had engineers, medical doctors, mathematicians and even Mensa members come back after as much as several years, convinced that Pentangle is impossible. On the other hand, we have seen many teenagers and a few tradespeople solve it in minutes, only to wonder what all the fuss was about!

I had read this a while ago and remembered the description and puzzle, which was why I was able to recognize it despite not having tried it. You can also purchase it at Puzzle Master under the name Fantastic Five, which appears quite similar (shown on the right).

As promised, this puzzle did end up being extremely difficult. I have been working on it on and off for the last six months or so. I took it on the flight to IPP 30  in Japan hoping that with enough time I would be able to crack it. Unfortunately, I did not have any success. Obviously going around the pentagon doesn't really do you any good, but if you slip the ring through one of the doubled-over pieces, you quickly become stuck.

As I mentioned in my last post, I recently solved Chain Gang, another devilishly difficult disentanglement puzzle. I realized on Saturday that I might be able to use what I learned on Chain Gang to approach Pentangle in a new light.

As I headed out the door on Saturday to Eureka Puzzles over in Brookline, I decided to throw Pentangle in my pocket and try to solve it while I was on the subway. I fumbled around with it a bit while waiting for the train, but didn't have any luck. I was just running through the same things that I had tried again previously.

Then, all of a sudden, it clicked! What had helped me solve Chain Gang was to observe a peculiarity in the design that I inferred must be related to the solution. I noticed that Pentangle also had a peculiarity that was somewhat similar, in a way. Using this, I tried something that felt new, and indeed it was! Exhilarated that I was on the right track, I quickly found the last few moves to get the ring off. Woo hoo! It is always exciting when you defeat a puzzle that has been stumping you, and I this one had been stumping me for quite a while!

The solution is pretty tricky, so I am not surprised that it took me so long to find it. I would be a bit surprised to see a novice solve it quickly as the Livewire description notes they have seen, but who knows!

I can't really speak about the differences in the design and construction of the three versions of this puzzle, but it is probably easiest to find either Pentangle or Fantastic Five rather than the version I tried. Looking at the pictures, I think that the solving experience will be fairly similar. The construction of the version that I have is fine, with a decent gauge wire and a good finish. Rather than the wood beads in Livewire and Puzzle Master versions, mine has coiled spring beads, which gave the puzzle a nice uniform silver appearance. Overall, a great puzzle that you should definitely check out if you like wire puzzles and don't mind a challenge.

Chain Gang

Chain Gang is another puzzle sent to me by Puzzle Master to review. This puzzle was originally designed by Dick Hess (name "Outrageous Rings") and was adapted for Puzzle Master by Allan Stein, one of the owners of Puzzle Master. Dick Hess is a very prolific designer of wire puzzles that can be quite difficult. One of them, The Yak, took me about a year to solve, you can read about that here: My Puzzle Nemesis Vanquished!

This one wasn't quite as difficult, but still had me stumped for quite a while. It is nicely crafted out of sturdy wire, with a big heavy ring on one end. The object is to get the oval ring off.

If you look closely at the picture, you can see that it is sort of like a chain that passes through itself. Starting at the big ring at the top, it loops down through the middle of itself, then at the bottom it turns to the left and passes through its end. It goes back up on the left and turns right at a ring (where it passed through itself near the beginning), and on the right hand side it swoops around back down to the ring at the bottom, where the chain terminates.

It is a bit tricky to see what is going on in the metal version, but Marcus Gotz created a version that was made out of rope named Double Edged Thought which was part of his IPP29 exchange Six Serpentile Strings. I found that it was quite a bit easier to see what was going on here.

Still, I was pretty stumped. I carried this puzzle around in my pocket for about two weeks, working on it here and there. I drew a diagram of it on a sticky note, hoping that I would arrive at some inspiration by staring at it. Unfortunately, none of this did the trick. Unlike some puzzles where it takes a little while to figure out that you're at a dead end, I was having trouble making any sort of progress beyond the starting point.

Finally, this Thursday night I had both some free time as well as a firm resolve to solve this damn puzzle so I could write about it. I worked on it for about a half hour and felt like I was starting to make a bit of progress, but again I was stuck. I was a bit discouraged so I set it aside for a bit, hoping to return to it later. When my fiancée, Kellian, arrived home, I told her about the trouble that I was having with it and explained  the different things I had tried.

Then she made an interesting observation about the construction of the puzzle that I hadn't noticed before! Indeed, it was an unusual feature that must have been placed there for a reason, and I figured out the reason. This focused my search for a solution somewhat. About 15 minutes later, I had solved it! I think in all I must have spent at least 3-4 hours on it. What a relief to have it done!

The solution is quite tricky: even after I had solved it, I wasn't exactly sure of the mechanics of what was happening. I re-solved it a number of additional times and now feel like I have a better handle on it. It is definitely not something that I could have come up with just by staring at a picture if it.

George Bell was kind enough to send me a photo of Outrageous Rings, shown here. It looks like the main difference is that Chain Gang has the addition of a smaller diameter ring before the final ring in the chain (the silver one, not the gold one). Also, the two straight pieces at the bottom of the Outrageous Rings photo are of equal length in Chain gang.

Overall, I'd say that Chain Gang is a great puzzle. It looks darn near impossible at first, but if you keep at it you'll discover a clever solution. Another great design by Dick Hess! I think I might have preferred Marcus's rope version, since it is a bit easier to tell what is going on. The metal version gets quite confusing with all of the rings rattling around, though I guess that's part of the point. It is a matter of personal preference, I suppose.

Thanks again to Puzzle Master for making this review possible!

Rik's Egg Balance and Around the World

Rik's Egg Balance and Around the World are two more of the 2010 IPP Exchange puzzles I borrowed from George Bell. Rik's Egg Balanced was presented, designed, and made by Rik van Grol  at Buttonius Puzzles & Plastics. You probably know Rik from his publication Cubism for Fun, a booklet published three times a year with articles written about puzzles.

The goal of this puzzle is pretty classic: to get the egg to balance on its short end. This type of puzzle has been done a number of times and as Rob Stegmann notes, the U.S. Patent Office devotes an entire sub-class to "Balancing Ovoids" (ccl/273/154). This one is made out of plywood that has been laser cut and glued together.

Of course, you can't just stand it on its end by balancing it carefully. You need to first manipulate the puzzle in a certain way to get it to balance. You'll immediately notice that there are a few things rattling around in there. If you shake the hell out of it, you may end up with a ball bearing visible through the hole that the arrow points to (which goes all the way through the puzzle). It takes a bit more of a deliberate method in order to actually solve it though.

I think it took me about 5 minutes of rattling around before I solved it for the first time. What I didn't like about this one is that there wasn't an 'ah hah' moment, it was just some methodical manipulation until it worked. Perhaps there is a more clever way of solving it, but the way I found has only a moderate chance of success. Still, I can solve it in about a minute or two this way.

I tried this one out with my family to see how they found it, and most just rattled it around a bit before giving up. I think this type of puzzle is not as compelling as some other types because you don't really know what is going on. You have to make some educated guesses and go from there, which is how I figured it out.

Around the World is an assembly puzzle presented and designed by Kozy Kitajima. The illustrations on the pieces was done by Miwa Miwa.

This is another laser cut puzzle, but this one is made out of what appears to be fiberboard. The goal is to place the pieces so that the 8 pieces create a closed loop. Not all of them are shown in the photo.

Like a lot of puzzles of this type, I wasn't really sure where to start, so I just started messing around a bit hoping I would stumble upon the solution. However, when I got to the last few pieces I could see that it wasn't going to work out.

There is probably some logical way to figure this out, but I decided to try brute-forcing it by trying every possible combination of pieces. Fortunately, the pieces are numbered, so it was pretty easy to keep track of where I was. If you just look at all the possible permutations, there are 40,320, but since it is cyclical there are only 5,040 different distinct ways of arranging the pieces in a circle. This may seem like a lot, but sometimes you can tell that the first four pieces cannot produce a valid solution if there is no way to get back to the start.

I think I was about 1/7th of the way through the permutations in 30 minutes before I stumbled across a solution that worked. Phew! If that sounds like a lot of tedious work, it was! Assembly puzzles are not one of my favorite types, perhaps it is because I make them laborious by using techniques such as these. Any suggestions for a better approach?

Thanks again to George for loaning me all these puzzles! I've got about 6 left to write about, though two I haven't solved yet. I need to get cracking!

Plus Puzzle

Plus Puzzle is another one of the 2010 IPP Exchange puzzles I borrowed from George Bell. It was designed and presented by Edi Nagata.

One unique feature of this puzzle that you'll notice right off the bat is that it was made out of LiveCubes (puzzle building blocks) that have been glued together. I've previously written about LiveCubes here. Some folks may not like that it is constructed this way, but it didn't really bother me. I think that Edi actually is the inventor of LiveCubes, so it is not surprising that he used them for his exchange puzzle. Since they are glued together, I was a bit concerned that they would break easily, but it ended up being pretty sturdy.

The purpose of this puzzle is to change it from the shape shown above, to the shape shown on the left. There are little nubs that fit together when it has been solved. You can sort of see the green nub in the upper left corner of the cross above.

It consists of two identical interlocked pieces, and requires a number of rotational moves to solve it (around 6-8 moves, depending how you count). It doesn't come completely apart, though the design could probably be modified somewhat to enable this. If that was done, I think it would make a great addition to Hanayama's Cast Puzzle series.

I found it moderately challenging, it took me about 10 minutes to solve. I found one of the moves to be  unintuitive in a clever way, which I think is what makes this one challenging. There is different point that I found physically difficult to navigate even when I knew the solution. You need to have the pieces lined up just right to make it happen.

It is also a bit of a challenge to get it back to the start, though of course somewhat less so if you paid attention to what you were doing in the first place. I got stuck briefly near the end, but eventually figured it out.

Overall, a nice puzzle! I like the fact that a puzzle with rotational moves like this can't be solved by a computer easily. I guess the only slight downside is the construction, but I didn't mind that much. You would certainly have to be less careful with it than if it was made out of nicely finished exotic wood! I do think it makes it a bit less compelling to play with though: I brought it to Thanksgiving at my family's house, and I think only one person attempted it (unsucessfully). Also, the 'solved' state isn't quite as satisfying as having the puzzle come apart, and it was a bit difficult to explain to a non-puzzler.

Still, it is a good puzzle that I enjoyed solving. Thanks to George for loaning it to me!

The Big 30

The Big 30 is another puzzle sent to me by Puzzle Master to review. This puzzle was designed by Allan Stein and presented as Allan's exchange puzzle at IPP 30, hence the shape. Cute, eh? I had seen this puzzle during the exchange, but hadn't gotten a chance to try it, so I was interested to see how it was.

The goal is to remove the zero from the three. As you can see in the photo, the zero is just looped around the three, with the gold chain and ball keeping it from being removed.

After a few moments of playing with this one, I had a pretty good idea of what needed to be done. Of course, sometimes knowing what needs to be done is easy and actually doing it is tough! In this case however, I was able to figure it out pretty quickly. I think it took me less than a minute.

I was interested to see how difficult other non-puzzlers would find it, and was quite surprised to find that they actually had a good deal of difficulty with it. Watching folks try to solve this one was a bit like watching somebody try to push a "pull" door, it seemed so obvious to me, but clearly it was not. Most gave up before solving it after playing around with it for a 5-10 minutes. A particular part of the solution is a bit un-intuitive, so I think that is where folks were getting hung up. A good puzzle takes advantage of these mental blocks to stump you!

The folks at Puzzle Master rate this as a 6 out of 10 difficulty, and I am inclined to agree, though perhaps it should be a 7. I think it is about the same difficulty as the last puzzle I wrote about, Panic Attack, if not slightly harder. Still, my sample size is a bit small so who knows! I think it really depends how much experience you have with this type of puzzle.

Overall, a nice little puzzle that is well designed and crafted. It was a bit too easy for my taste, but I did enjoy showing it to other folks! Thanks again to the folks at Puzzle Master for sending it to me!

Panic Attack

Panic Attack is another puzzle that I received from Puzzle Master to review. This puzzle is designed by Kirill Grebnev and manufactured by PuzzleMaster. Kirill has also designed Harmony, which won the Puzzler's Award and Jury First Prize at IPP30 in 2010, and Forest Puzzle which won an honorable mention at IPP27 in 2007.

Like all of their wire puzzles, the quality is great. The wire is a thick enough guage to be sturdy, but no so much that it is heavy. It has a nice shine to it as well.

The objective is pretty simple: remove the yellow loop from the heart. I like puzzles that appear simple like this one: only two pieces! It reminded me a bit of Iwahiro's Dinghy, where you are also removing a flexible loop from a wire structure.

At first, it looks fairly impossible, which is always a good thing for a puzzle like this. However, there aren't very many dead ends, which made it pretty easy. I think I solved in about a minute or so. I brought it to a family gathering and some people had a much easier time with it than others. Most had the right idea, but it must be executed in the correct way. I think this is a bit easier than an 8/10, maybe closer to a 6/10, but it really depends.

As for drawbacks, the only thing I can think of is that rope is just a hair too short for my taste, but it probably varies a bit and some may actually prefer it this way. Overall, a fun puzzle that has a nice simplicity. A great design by Kirill Grebnev! Thanks again to Puzzle Master for sending it to me to review!

Meffert's Pyraminx

I'm not typically a twisty puzzle fan, but recently Puzzle Master sent me some puzzles to review, and Pyraminx was one of them! This was actually the first puzzle designed and produced by Uwe Meffert way back in the 1970's. The Pyraminx has so far sold over 90 million copies world wide, making it the second most popular puzzle in the world! 

I had seen photos of it before, but I wasn't quite sure how it rotated, so I was interested to give it a try. It is actually one of the easier twisty puzzles out there, which also appealed to me since I'm not particularly good at them.

Each of the four corners rotates independently, so those are quite simple to position. If you go down one level from a corner, it can also rotate along that axis, which consists of the corner, three edge pieces, and three middle pieces. You can't rotate a single edge, which I found myself trying to do a few times before I got the hang of how it worked.

It turns quite nicely, and has spring loaded ball bearings that lock it into place when you complete a turn. This gives it a nice clicking noise as you solve it. I was also impressed by the weight of the puzzle, which gave it a nice feel.

Since it wasn't supposed to be too tricky, I scrambled this one right away and gave it a try. After about 5-10 minutes I was able to get all but two pieces in place, but those last two vexed me. In my attempt to get them positioned properly, I managed to screw up the rest of the puzzle, so I essentially had to start over.

At first I was just trying to get one face to be all the same color, but just randomly twisting with that purpose in mind wasn't doing me much good. Eventually, I figured out a move that would bring a piece into the correct position. Interestingly, this is quite similar to a move that I learned to use on 3x3x3 cubes, but it is pretty intuitive.

Again, I got to the position where only two pieces were off, but this time in my attempt to get things in the right spot, it all came together! It was a nice little surprise, but I wasn't quite sure how I did it. In total, it took about 15-20 minutes.

Not content with not knowing how I finished it, I decided to scramble it and try again. This time, I had a more methodical approach, and was able to solve it in several minutes. It really isn't too hard because there are only six pieces that are a challenge to position: the six edge pieces. The others are either quite easy to fix, since you can just twist the corners to match up to their adjacent piece, which doesn't move when you rotate the puzzle.

I can't really think of a negative aspect of Pyraminx, it is a lot of fun! It is a good one to try if you're just getting your feet wet with twisty puzzles. If you're good at them, you may find this to be too easy, but you'll probably want it in your collection anyways. Thanks to Puzzle Master for sending me this puzzle to review!

Six Piece Cross and Icosahedron

I recently borrowed a number 2010 Puzzle Exchange puzzles from George Bell, one of was Six Piece Cross by Vaclav Obsivac (a.k.a. Vinco). It was presented by Patrick Major in the puzzle exchange at IPP 30. I don't see it on Vinco's website, but you can purchase it at Puzzle Master if you are interested.

Vinco makes some interesting puzzles, many of which operate on similar principals but have different appearances. This one has a similar operation to his Flattrick puzzle, though the appearance and mechanism are quite different.

There are six pieces, like the one shown here, that all slide together at the same time (coordinate motion) to create the shape shown above. It seems fairly straightforward, but in practice it is pretty challenging to get the pieces lined up just right to slide together.

I had done a similar puzzle before, so it only took a minute or so for me to solve, but it is definitely not easy. My girlfriend tried it out for a few minutes, and it drove her fairly batty: frequently you get very close to finishing, but the whole thing falls apart in your hands.

As with all of Vinco's work, the craftsmanship is nice with perfect fit. It has a natural finish, and is constructed out of walnut and plum, though Vinco frequently uses different woods for the same puzzle.

Overall, a solid puzzle that I enjoyed. I think the one downside to this one (and this type of puzzle in general) is that the solution is a bit fiddly. It does take a fair amount of dexterity to solve it, but it is quite satisfying when the last piece pops into place and the whole thing slides together.

Another Vinco puzzle that George loaned me is called Icosahedron. This was actually Vinco's own exchange present for IPP 30.

It is a bit hard to see in the picture due to the wood grain, but it is an icosahedron as you would expect from the name. This particular one is made out of a nice dark wood, though there were other versions available.

Since he has been doing a lot of coordinate motion puzzles recently, I expected this to be a coordinate motion puzzle as well. I had fiddled with it a bit at IPP, but didn't have any luck, so I was glad that I had the opportunity to try it again.

After a minute or two of fiddling, I was able to get it to come apart. It actually consists of four pieces, though there is no coordinate motion. I don't think most will find it particularly challenging. My girlfriend was able to get it apart in a few minutes, though she had trouble getting it back together. Getting it back together is tricky, because things need to be lined up in a way you may not expect.

As a puzzle, this one didn't interest me as much. However, the craftsmanship is superb: the pieces fit together just right. This puzzle is quite a bit smaller than the previous one. It is a bit more than an inch tall, I think. It has a smoother finish, which may be a property of the wood used. Overall, a nice little puzzle.

Thanks to George Bell for loaning me these puzzles!

Cast Rattle

I had actually tried Hanayama's Cast Rattle about three months ago during July, since it was an entry into this year's puzzle design competition in which it won an honorable mention. I had only spent about ten minutes or so on it at the time, since I figured it would be available soon and I wanted to spend my time at the competition trying out puzzles that I wouldn't have the chance to try again. I just had the chance to try it out again, courtesy of Puzzle Master!

It is an interesting design by Bram Cohen that consists of four pieces that rattle around, hence the name, but stubbornly refuse to come apart. The pieces appeared identical, and it is pretty obvious that there is no hidden mechanism, so it is a bit puzzling what keeps them from coming apart.

The finish on this puzzle is nice and shiny and  it has a nice weight in your hand, as is the case with most of Hanayama's Cast series of puzzles. The fit is prefect, with no force necessary but no unnecessary slop either in the solution. That said, it does rattle around quite freely and somewhat lacks the elegant and stable resting position of something like Cast Vortex, the first puzzle I got in this series. This is really the only downside to this puzzle for me, but there's not much that could be done about it.

I started out just fiddling around with it a for a few minutes like I had done at IPP previously, and similarly didn't end up having any luck. Clearly just fiddling with it idly wasn't doing the trick, so I needed to take a more logical approach. Depending on how you slide the pieces, you can see every part of them, so I was able to take a logical approach that ended up leading me to the solution. This was quite satisfying, since there was a nice "Ah hah!" moment when I figured out what I had to do, and after a minute or so I was able to execute the solution correctly. In total, I think it took me about 10 minutes. It only took me a minute or two to get back together since I had a pretty good understanding of what I had done.

I think this would be an appealing puzzle to hand to somebody, because they can get it to move around a lot, which feels like they're making some kind of progress. However, you really have to stop and think about it to find the solution. I tried shaking the hell out of it, and that didn't work for this one, which is always a good thing.

In terms of difficulty, I would agree with Hanyama's rating of 4 out of 6, it of similar difficulty to the others with that rating such as Cast Baroq. I think most will be able to figure it out within 20-30 minutes, though I know a pretty smart fellow who spent an hour on it! It just depends when the inspiration strikes you, I think.

Overall, Cast Rattle is a solid puzzle that has a beautiful simplicity to it and a clever solution. Definitely worth picking up if you're into this type of puzzle! Thanks to PuzzleMaster for sending me a copy to review!

Note: I've recently set up an affiliate arrangement with PuzzleMaster so I get a small percentage of the sale price if you buy puzzles from them using the links I provide. They're also sending me some free puzzles to review. Of course, I honor your trust and will do my best to keep all reviews as objective as possible and continue to give you both positives and negatives for every puzzle. Thanks for reading!

Newton's Egg by Stephen Chin

This puzzle was Stephen Chin's exchange puzzle at IPP30 in Japan. I had seen photos of Stephen's work before, but this was the first that I have had the pleasure of trying.

The goal is to open the egg, and the hint is that it is based on Newton's three laws of motion. This particular copy is made out of Huon Pine, which gives it a nice aroma. I was intrigued by the hint and decided to buy a copy.

When I got it, it arrived it a plastic tube and was wrapped in a kid's sock. It also included a tippe top made out of colored pencils that had been glued together and turned on a lathe! This is one of Stephen's 'signature' techniques. It also included the captured ring stand you seen in the photo on the right. The ring can't come off the stand because the diameter is too small, so it is sort of an impossible object. Of course, he achieves this by carving both the stand and the ring out of a single piece of wood. Stephen is a master of the lathe!

It is quite nicely crafted, with a smooth finish. At first, it looks completely impenetrable. I had no luck just trying to take it apart, so I figured there must be a locking mechanism of some sort. I immediately noticed that there is a rather pronounced rattling when I shook it, so I thought it might have some kind of gravity mechanism.

When I actually figured it out about 10-15 minutes later, I was quite surprised at the simplicy and cleverness of the mechanism! It is simple enough that I would have thought it had been done before, but I'd never seen anything like it. Additionally, it could not have been possible if it weren't for Stephen's excellent craftsmanship. It is a fun one to open, I find myself going back to it now and then just for kicks. Once you know the trick, it isn't hard to do, but folks could struggle with this for a little while their first time.

Overall, this is a great puzzle and I'm glad that I got it. I look forward to seeing what Stephen will come up with next year!

TenPlate Puzzle

As I mentioned in the Part 5 of my series of posts about the 2010 Rochester Puzzle Picnic, Jeff Aurand gave a talk about writing a computer program to solve all TenPlate puzzles. At the end of his talk, he had a drawing for a copy of this puzzle, and I won one!

I hadn't had a chance to work on it until now, and I was curious to see how difficult it would be to solve manually. In this photo by Jeff you can see it in one of its solved positions. There are a number of solutions to it, though Jeff would have remind me how many.

The puzzle consists of ten flat pieces. There are five notches, each of which can either be tall or short. Each piece has a different combination of notches. They can be arranged as shown above to create a cube.

This puzzle was designed and made by Jean-Claude Constantin and was Luc De Smet's exchange puzzle at IPP28 in Prague. It is nicely laser cut with what appears to be a veneer of some sort, which gives it a pretty good finish for a laser cut puzzle.

I worked on it for about 20 minutes before dinner one night. My strategy was to just guess at the location of a particular piece, and try to find a combination of the other pieces that would work. When a particular arrangement wouldn't work, I'd rearrange a piece or two in hopes of remedying the issue without screwing something else up. I hoped that I had picked a location that would work for that first piece! Unfortunately I ran out of time that night and had to return to it the next day.

The next day I had a bit more time, and again continued down the same path that I started the previous day. After about 30 more minutes, I was cursing the fact that the last piece wasn't going to fit yet again. However, upon closer inspection, I noticed that it would! I was quite satisfied as the last piece slid into place.

The one thing that bugged me about this puzzle was the difficulty in lining up the pieces. Since they are fairly long, it is hard to get them quite lined up so that the grooves slide together. On more than one occasion, I would be lifting the puzzle up and wiggling pieces trying to figure out why it wouldn't slide together, only to have another piece fall out of place.

Also, it is a bit of a dexterity problem to try to get a piece out of the bottom layer without everything falling apart. I ended up just taking off most of the top layer before messing with the bottom layer, since that was usually safer.

A similar puzzle that avoids these issues is StabPuzzle by Logika Spiele. Logically it is the same idea, but physically the pieces are different. This particular puzzle is a bit simpler since it only has 8 pieces rather than 10, but the same idea could be adapted to this 10-piece puzzle. While it may be easier to manipulate, it doesn't look quite as cool as TenPlate or stay together as well.

Rob Stegmann's website has quite a bit of information on this group of puzzles, which he calls Crossed Sticks puzzles. He even wrote a solver that could solve variations of this puzzle up to 5x5. Pretty cool!

Overall, a nice little puzzle. I would say that it is fairly difficult, you'll need to be either lucky or patient when solving this one. Thanks again to Jeff for giving it to me!