Introduction: Cardboard Puzzle Box

One of the fascinating trends of the internet I've taken notice to are the impossible boxes. Now that sounds quite daunting, but when you look further, this impossible box is simply just a 3D puzzle that may contain a storage compartment or a small item. I had been most interested in the boxes with storage inside because it intrigued me to think that there could be a better method than a toy safe to keep things in. So after a while of thinking and brainstorming, using the engineering design process, I came up with a simple version of this that is easy to open if you know how it works.


  • Cardboard
  • A Ruler
  • A knife or box cutter
  • A hot glue gun
  • Packing Tape
  • Paint or other coloring tools (Optional)

Step 1: Step 1: Measuring Your Pieces

The first thing you want to do is measure out the pieces before you cut. Attached to this step is an image of the measurements and pieces (not to scale). You will need 3 6"x6" squares, 2 6"x6" with 1/2"x1/4" holes and one of each of the other pieces. Trace the patterns on the cardboard.

Step 2: Step 2: Cutting Your Pieces

After measuring out the patterns, you will cut out the pieces using a knife or box cutter. Carefully cut out along the lines and lay out your pieces.

Step 3: Step 3: Assembly

Place the piece with the 2"x1/4" hole on a safe surface to glue on. Place one of the pieces with a 1/2"x1/4" hole by the hole side of the one on the gluing surface with the small hole up and the solid part towards the bottom piece. Glue these together. Place two of the solid 6"x6" pieces beside it beginning to make a cube. Add the third solid piece to the to the top leaving space open directly across the smaller holed square. add the key shaped piece before adding the roof. This is where the last 1/2"x1/4" piece will mirror its counter part making it easy for the lock mechanism to work. Tape the piece so it opens similar to a draw bridge. assemble the locking mechanism.

Step 4: Step 4: Final Testing

After you have Completed assembly go through tests. You should be able to lock the device by sliding the bottom tab and be able to pull the "key" or the spoon shaped item without the device opening. If you are able to, something is wrong, try and see what happened or what might need to be edited. Make changes accordingly.