Introduction: Combination Puzzle Box 3D Print

About: I like to design and build random things.

I purchased a version of this puzzle box a while back. The goal is to open the box by manipulating the keys on the ends of the box. I found it somewhat challenging with the trial and error solution.

I decided to make a 3D printable version of it with some modifications to allow for printing. The cool thing about printing is that you can decide on your own key layout so the solution can't be looked up online. Although I think I modeled it correctly, I haven't printed it yet so I'm not positive all the dimensions will work. I will give an Instructables membership to the first one that prints it and publishes pictures in the comments. The STL files are included for printing (last step). I've also included STP files for those that would like to modify the design.

To not leave the woodworkers out of the loop, I've included dimensioned parts as well (see PDF).

Below is a video of the wooden version.

This video shows the animation of the modeled version.


  • 3D Printer
  • Adhesive

Step 1: Drawing

This the top-level drawing. My version is slightly larger than the wood version. The gaps between parts are modeled as .005". All parts are color-coded for reference. I tried to make everything printable without support structure. Unfortunately, this requires a few parts to be attached with adhesive.

Step 2: Box Base/Sides

The base of the box measures 5" x 3". Two of the sides are incorporated into this piece as well. I decided on 1/4" thickness for all the walls. The notches in the base are used to help align the remaining sides during assembly.


Step 3: Sides

The other two sides are almost identical. The only difference is a small hole in one of them to use as a reference point since the box is symmetrical. The notches fit into the slots on the base.

Step 4: Keys

There are two style keys for the puzzle. You will need to print 10 total. Although the picture shows two colors, I would print them in the same color to not give away the solution.

Step 5: Base Assembly

I suggest studying the cross-hatched views in this step and watching the animation before assembling the base. Note that I'm showing one open side (section A-A) and one locked side (section B-B) in the graphics. This might be easier to see on the complete assembly (Step X).

Starting with the sides, layout the keys in the desired order. Note the orientation - thin blocking strip on top. Next, move the sides/keys to the base. This connection will eventually be glued but I suggest temporarily holding it in place for now. Write down the combination now! Note that drawing a picture (hole side for reference) would be a good idea.

Step 6: Lid Parts

The lid is broken into two parts to aid with printing. Both parts can be printed flat without the need for support. Print one cyan part and two of the marroon part.

Step 7: Lid Assembly

Do a quick fit check of the cyan part to make sure it fits inside the base (should be 1/16" gap per side). Glue the parts together as shown. Note the orientation of the pins.

Step 8: More Fit Checks

At this point, I would do one more fit check. If everything is good, glue the base pieces together. You have now finished the puzzle. Again, write down the combination.

Step 9: Finished Puzzle

Please let me know if something doesn't fit or you need clarification.

Step 10: 3D Print Files

Attached are STL files. Print the following:

  • 1 Base
  • 1 Lid
  • 2 Lid2
  • 1 Side1
  • 1 Side2
  • 5 Slide1
  • 5 Slide2

I've also included the lid assembly if you would like to try to print it as one piece.

Thanks for viewing!