Community challenge #12: Puzzles (closed)

Ha! Sorry to create the stir.


Sorry, I got all excited thinking you would be making this on a Shapeoko, per the rules :wink:
But it would be interesting to watch that process in action.


The Attribute Mazes have names based on guiding Dungeons and Dragons attributes. (Of course, any puzzle can be solved with enough Strength or Charisma). The objective is the same for all three mazes: guide the ball bearing from start to exit without turning the puzzle upside down. The bearing is 0.25" and the puzzle dimensions are 4" x 2.75" x 1.125".

  • WIS (Wisdom): a perception check; find the magnet to guide the bearing past the holes in a simple maze
  • DEX (Dexterity): a tricky spiral ramp must be navigated so the bearing can fall through the center and exit
  • LOG (Logic): a lever-activated double-trammel mechanism allows the bearing to avoid a T-shaped trap


I would like to continue making these types of puzzles with the attribute as a hint and puzzle names like WIS+1. I am especially proud of the trammel mechanism because I’ve never seen that in a puzzle before. I was inspired by the Trammel of Archimedes and wanted to figure out how to put it in a puzzle.

For each puzzle, the process was:

  1. Prepare stock at correct thickness
  2. CNC the puzzle base and lid (using only 0.25" end mill) using Shapeoko hardwood settings
  3. Create auxiliary pieces (ramp, trammel blocks, lever)
  4. (Drill dowel holes and) add dowels; attach lid
  5. Hand sand until satisfied (320 grit)
  6. Engrave puzzle name on lid with 60deg V-bit
  7. Finish with Danish oil and a coat or two of shellac


I had some fatal mistakes here in the final steps that have put this project into the “remake later” category. This should have been the easiest puzzle to make. The maze is simple but the ball will fall out the bottom if the magnet is not used. The maze must still be “mapped out” because moving the magnet in the wrong way will drop the ball. The magnet is hidden in one of the four dowels (with the other three glued in). Major mistakes:

  • I thought I could hand-drill a straight 3/8" hole through the bottom piece, guided by the top piece. I should have used a drill press or trusted the CNC.
  • My dowels are too thick for the holes; I should have taken the time to sand them down! I ended up cracking three out of four corners while hammering them in.
  • The first hole can be bypassed by quickly tilting the puzzle, giving the ball enough momentum. But I haven’t been able to build enough momentum to bypass the second hole, so I consider the holes well-placed.
  • I lost my magnets! They must be stuck to something metal because I can’t find them anywhere right now. Also, check your magnet strength before you put the lid on to make sure they are strong enough.


The trick here is to gently guide the ball up a spiral ramp and into the center hole, where it drops down and easily exits. I made the raised ramp out of MDF with the idea that it could be sanded and sculpted to make the task easier if necessary. My version is tricky even if you can see the ramp, so I will be adding a slight groove to the ramp using a chisel or carving tool.

  • In my first design I didn’t pocket quite enough space in the top piece to allow the ball all the way up. This was straightforward to fix with a chisel, but it definitely doesn’t look great.
  • A simpler design would probably be a better starter puzzle (for example, a round container with an internal, square wall and a single opening).



The double-trammel design here means a single lever moves the two wooden blocks in a slightly confusing manner, but the mechanism is visible through the holes in the boxes. Each block has two holes to allow the ball through. A shortcut can even be used to bypass half of the maze.

  • Solidworks was useful for the initial dimensions because the constraints are easy to set and test. Fusion360 may work just as well, but I’m not very skilled yet.
  • I used cut-off nails with wide heads to hold the trammel blocks to the lever.
  • If you know of any other puzzle that uses this mechanism (especially with more than 1.5 tracks) let me know – I’m very curious what else can be done!



It’s not much to watch. The workpiece is submerged in water with a splash guard over the top. all you really see is the wire feeding.

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Does anyone else have fun with naming their gcode files?

Finally making some headway on my entry after settling on some adjusted dimensions to get the parts to “smoothly” fit. I had a heck of a time getting the small piece tweaked to fit in the bigger one…Fusion made it look simple with plenty of clearance :neutral_face:.


Optical Illusion are puzzles for the mind… and I’ve been wanting an excuse to try out @neilferreri 's F360 inlay technique from community challenge #5 for a while now… Albeit I wanted to give it some steroids.

Next, I wanted to find a less time consuming way of making optical illusion cutting boards such as these: (careful this video will make your head hurt if you really think about the how)

End Product, End-grain Optical Illusion Cutting Board:

Nah, just flat:

Identical to Neil’s tutorial with the exception of having to use 1/16" tooling because my .125" bits would not fit in between the sketch contours with the 30deg wall taper on the roughing/clearance steps.

Toolpaths / F360 file:

Biggest Lesson Learned… Do the male side second. Whenever your remove the bulk of material from one-side of a piece of wood but not the other you introduce stresses that warp your piece. I did the male side first because I was afraid of messing up the engrain walnut block… but by the time I got to the female side the male side had warped such that it took the clamping force of a small car to get everything to chinch down (yes, there are “cauls” on the other side).

PS Public thank you to @neilferreri for hand holding me through several moments of “this can’t possibly work”.


@MarkDGaal NICE! That turned out great. I know I kept saying to “trust the math”, but I was nervously waiting to see the result.

You’re welcome…I’m glad someone took me up on it. So cool that you can do that from just a single sketch.


So first a brief history to give some context. My mum’s family used to wrap each other Christmas presents in such a way as to make it difficult/annoying to open. For example, imagine wrapping a pencil, as the gift, in a small box, then wrapping that with some plastic to waterproof it. Finally, pour cement around that to encase in an approximately 18”x12”12” block of concrete. This was their way of entertainment.

Once I heard these stories, I couldn’t help myself, so I ended up “wrapping” my, at the time, girlfriends presents in such manners as to make it difficult for her but entertaining for everyone else to watch. This went on for a few years until she asked for me to make them more like a puzzle as opposed to need brute strength and power tools to open. So now every year I need to come up with a puzzle/riddle/maze or some combination thereof to wrap my wife’s Christmas present. Needless to say this was definitely one of the reason for getting a Shapeoko in June.

Now that the history of why I do this is there, now lets talk about the project itself. For me, there are several firsts involved in making this.

-Machining metal on the Shapeoko, Thanks Winston/Carbide for the great S&F videos

-Designing parametrically in Fusion 360, at least initially, the design got a little messy towards the end after a few modifications to how parts interact

-Making an assembly with joints in Fusion 360, have only done individual parts or static assemblies before

-Finally, first time posting on this forum, been creeping a while though. And hopefully I can figure out how to post on cutrocket too . I think I got the fusion files posted to CutRocket

Finished product glamour shots:

Now to get into how I designed and made it. First off there were a few design considerations that I had in mind.

-The exterior just had to appear like a simple nice looking box.

-I wanted the maze section to be fully self-contained in the lid, so when opened it came off in one piece.

-I wanted the “start” to be hidden, so it’s not obvious where/how to start the puzzle.

-Finally, I wanted it to have a hidden path/wall, similar to top-down video games like Zelda.

The main section of the box is pretty self explanatory. Just a box with some fillets to add some design and aid in holding it while trying to solve it. The lid is really where all the magic is. To progress towards the center of the puzzle, the lid slides off to one side, and once you reach the center it can be simply lifted straight up revealing the contents.

But the pin that needs to travel through the maze is hidden off to the side underneath the top lid. So knowing where and how to start shouldn’t be abundantly clear. There are also 3 different start points to the maze, one of which is a dead end. As you can probably tell pretty quickly there is no obvious path to the center of the maze. This is where that hidden path I talked about earlier comes into play. In person, it is very difficult to see that the wall isn’t actually a wall, but if u just keep turning the maze, it will slide right on through the “wall”.
Photo highlighting the fake walls and dead end trap

Now the whole process of making the individual parts didn’t go perfectly, I had to make a few versions/copies of a couple pieces because of tolerances and or slight design changes to make everything function better. The wooden lid for example, when making the initial design the wood chipped out because there was such a thin feature. Which warranted the slight redesign to help lower the chances of that.
Once I was happy with how everything was dry fitting together I glued the box together and then I finished the Oak with Tung oil.

Luckily my cat was on hand to provide supervision…

Here is the box and lid assembly after it was finished with the Tung oil.

For how much I stressed out about cutting metal for the first time, I think it went quite well. Nice chips, quiet cutting, and pretty good surface finish right off the machine.

There are a couple things I may eventually fix up in a refined version.

  1. The brass maze has a little more flex in the middle then I would like, this could be easily fixed by tweaking the maze construction and adding a couple more walls.

  2. Change up the order of operations slightly when cutting the maze section to ensure perfect alignment when flipping the stock.

  3. Clean up all the small tweaks I made after the initial design so the box can still be parametrically altered.

  4. Designs other, more complex, mazes and hopefully figure out a way to program a random maze

Overall though I am very happy with the end result, now I just need to figure out what to get my wife for xmas……

I imagine I also glossed over a few things so if you have any questions, just ask away.


I knew you guys were preparing some fantastic entries !
Also, I like the new trend of including pets in the project pics !


Life got in the way for me entering this competition but what a rip-snorter so far!!! Some incredible entries! Voting going to be harder than ever!


Nice work guys :fire:!! I agree voting will be difficult.
I just lost my last aluminum-cutting endmill (on a spring pass of all things :roll_eyes:) so I’m waving the white flag for my project…I’m starting to learn my lesson about procrastinating with these haha!

A fun challenge with tons of creative entries everyone!


Can you share your end design, @dakyleman ? A radial, 3-fold symmetric jigsaw puzzle?

Glad to see CutRocket is running again. I am editing in some links and pictures into my 2 posts so please have a look after the weekend… Still one puzzle left to complete!

I finished reading through “Professor Hoffman’s” Puzzles Old and New (1893). Some fascinating ideas in there, but most are suited to lathe-working. I really wanted to copy Stickman No. 20, which is based on an idea in the book. Two more links for future use:


I really love this theme of puzzles trying to understand and conquer a difficult set of sequences or principals. I have been toying with puzzles for quite some time and have built a few by hand a couple years ago pre CNC, so I thought I would give it a go and design a puzzle for this contest.

I would like to present “In-between a Rock and a Hard Place!”

The object of the puzzle is to remove the Key from the stone like Excalibur, by aligning the sliders in the right configuration with a little twist at the end :wink: Check this link for a video to see it in action.

It’s a relatively simple concept although you need to spend some time with it to develop a “feel” for how the sliders move and when they fall in place. It’s kind of like you are controlling the tumblers of a lock to release the key, it also feels like playing jenga too when you are hunting for the block with the least resistance. Once you have aligned the sliders the key will be able to be removed one inch; at which point the key will become stuck again. Then you have to twist the key and the whole top of the puzzle and BOOM the key is able to be removed completely. I love that It makes a really satisfying sound when you remove the key. All of the sliders can then be removed and mixed around to create a new sequence. I also like the fact that once you solve the puzzle you get to see in greater detail all the machining I did on each piece.

Here are the components involved,

You have what I call the “Inner Sanctum” which is made of HDPE and serves the purpose of structural integrity, and an accurate core for the workings of the puzzle. The Inner Sanctum is crucial for the final Twist. It also fills out the overall shape of the puzzle so it’s not just long and skinny.

The prize of the puzzle is the aluminum key. Only the bravest and most patient puzzler will feast their eyes on this mystical object.

And last but not least the outer shell. Made from cherry plywood added on to spice up the look of the puzzle and to give it some nice smooth contours. It also hides the slider tracks so you can’t see where the holes are. I would have loved to have made this out of black walnut but I never found the time to run to the store and get some because of all the problem solving I was doing hahah. Although to be fair I really like the look of the plywood end grain criss crossing on the sides.

This project was a huge learning curve for me, I think I have tried each of these machining principles in the past in one form or another but I have never done them to this scale or with the needed accuracy as this project demanded.

Here are the notable machining feats.

The slider handles came out great! With smooth fillets rolling into each other and a near mirror finish, needless to say I am very pleased. I used a roughing pass with a .25’’ upcut bit and then a ball nose bit with a .25mm step over. It took me a couple tries to get the step over and I realized after the first go that I could also machine the .125’’ round over on the edges.

The HDPE Inner sanctum was pretty fun to machine, HDPE is like cutting hot butter. Tolerances were the big issue for this part. The inner rectangles where the sliders run through needed .005’’ of each side so the .5x1’’ rectangle became .51x1.01’’ thought that .005 would do the trick on the box joints but there ended up being considerable slop in the joints. Therefore it ended up being no tolerance at all!

The Key required 4 sided machining, taking my aluminum experience to a new level. The key needs notches cut in on every side to make the puzzle work and to do this I followed a standard procedure for double sided machining. My bit was not the right length so I had to contour out the piece from both sides which wasn’t my original idea, but hey a plan never survives first contact with the enemy. I had to do some additional modeling for the key so I could get the machining to do what I wanted. I’m sure there are some fancy CAM settings I could have used but I could not figure it out. I was not a hundred percent accurate on my flip not sure where the errors came from (still haven’t figured it out) but it was acceptable, and I only had the one block of half inch aluminum to work with.
To do the 3rd and 4th side I made my very first fixture! This worked very well. I tested it once and got a perfect fit on the second go I took off .005” from only the horizontal sides when machining to allow the part to click into place. I was surprised at how sturdy it was and yielded an excellent cut.

The plywood exterior was pretty straight forward work on the cnc. Modeling it was pretty fun and again TOLERANCES changed because wood is different than HDPE. not surprisingly. I took off .03” of where the sliders came out to give it good action.

I made countless errors with many facepalm moments but it was a huge joy to design and build this. I have to say the time limit stressed me out a bit. It feels like I havent had to build a project on the clock since high school. I haven’t yet sealed the wood, but i’ll get to it real soon and post pictures.

My files are pretty messy and I will get to posting it on CutRocket soon but I need to consolidate everything I learned into singular files. Is there any way I can post my files now to make the dead line and then clean it up later?
I posted all the Gcode into a dropbox, does that qualify? heres the link.

Feel free to drop some questions about the process!


Heres the link to the videos I forgot to In the last post.


Sure, there’s no judging on the tidyness of the files, the point is just for people to have a chance to take a closer look at your toolpaths/settings, so just link to the messy ones for now, that’s fine. You need to link the design files not the G-code though (for the reason I mentioned).

Oh, and this is a fantastic entry and writeup, thank you!


Ahh thanks Julien my misunderstanding.
Here are my most recent fusion files,

The Inner Sanctum, sliders, and Key -

The plywood shell -


I love where this was going, I hope you will finish it anyway and report later ?


Well I know I keep saying it, but man there is some creative people in the community, some of these entries simply blow me away!! Feel privileged to be part of these contests! And for other lurkers out there do not be shy, like myself you may not win, but it feels great to be apart of it😁


Wish I saw this earlier. I would’ve left one (with less flutes) out for you to pick up!


Final day!
Lots of edits, it was quite interesting to go back and browse the thread from the top and see where you all ended up (well not quite, there are still a few hours left)