Elastic Cord Cube Puzzle

This is a fun puzzle that is pretty easy to make. The goal is to arrange the blocks into a 2 x 2 x 3 structure. Online, you will see similar versions with various names such as Elastic Cube Wooden Puzzle, Icon Mental Block and Elasti Cube Puzzle. I show you how to build your own from wood and have also included a 3D print file for those inclined to take that route.

This video shows the puzzle AND solution. Don't watch it if you want to try to figure it out on your own.

Supplies

Wood Version

• Wood - enough to make twelve 1" cubes
• Ruler
• Pencil
• Saw
• Sand Paper
• Finish (paint, stain, etc.)
• Elastic Cord ~ 1 foot

3D Print Version

• Enough material for twelve 1" cubes
• Elastic Cord ~ 1 foot

Step 1: Drawing

You will be building to this drawing. The chamfers are optional. Make 12 blocks.

Step 2: Blocks

I used a table saw to cut the 1" cubes. Mark the center of two adjacent sides.

Step 3: Drilling Holes

I started by using a 1/4" Forstner on the flat sides and drilled ~ 3/16" deep (not shown). This pocket made drilling the angled hole easier and also allows space for the elastic cord knot.

To produce the angled cut, I cut a V notch into a 4x4. This allowed me to easily hold the block at 45 degrees.

Step 4: Finished Blocks

Repeat the above steps to make 12 blocks. I used two types of wood to give contrast. I rounded the corners with a sanding block. Oil was used for the finish.

Step 5: Cord

Cut a piece of elastic cord to 12". I used 1/8 inch Round Heavy Strength Elastic Cord but any elastic cord roughly that size will work. The pictures above are from the 3D print versions.

Step 6: Assembly

Route the cord as shown in the images. Remove all slack so the pieces are touching. Apply tension and tie a knot in the cord to complete the loop.

Step 7: Completed Puzzle

Once complete, your puzzle should look like this.

Step 8: Solving

Although it only has 12 blocks, the solution isn't intuitive. I spent more time than I would like to admit solving it the first time.

Step 9: Solution - Step 1

As stated above, the goal is to stack the blocks in a 2 x 2 x 3 array. These pictures show the general principle. The red spacers show the breaking points between the levels. The next steps will show you how to achieve this solution.

Step 10: Solution - Step 2

Start by flattening out the puzzle. This is somewhat of a puzzle in itself but should only take about 30 seconds.

Step 11: Solution - Step 3

With the puzzle sitting flat on a table, rotate the outer sides towards the center as shown.

Step 12: Solution - Step 4

This step is hard to understand in pictures - I suggest looking at the video in the introduction. Anyway, you will need to rotate the upper row from the previous step so it builds a 2 x 2 x 2 section. Note that the 3rd row may now be positioned as shown.

Step 13: Solution - Step 5

If positioned as shown in the previous step, rotate the blocks around to complete the shape. This requires a twisting motion - you will figure it out :). That's it; you've now solved the puzzle.

Step 14: 3D Print

You will need to print 12 blocks. They can be any color or combination of colors. I printed red, silver, and black blocks. The STL file is included in this step.

Step 15: Assembly

Assembly is the same as the wood version.

Step 16: Assembled Pictures

Step 17: Final Thoughts

I'm very happy with how these turned out. Hope you enjoy making your own. Please let me know if you have any questions. Also, if you like this puzzle, take a look at my instructables page for plenty of others.