A STEM Project: Yoshimoto's Cube #2 - Two Rings of Twelve Triangular Pyramids Can Be Flexed to Create a Cube

Two rings of twelve triangular pyramids can be flexed to create a cube. I made a box to contain them as they are very flexible and will not stay in the cube shape.

Two halves make up the cube.

Twelve triangular pyramids make up a ring for a total of twenty four triangular pyramids to create a cube.

In this series of four blog entries, I will be recreating, in the style of, Naoki Yoshimoto's "Shinsei Mystery Puzzles". The word "shinsei" means application in Japanese. This blog entry will explore the puzzle entitled Yoshimoto's Cube #2. In 1971, Naoki Yoshimoto discovered a way to divide a cube into equal parts in three-dimensional space. The result was a series of three puzzles by Yoshimoto.  

This design is twelve flexible triangular pyramids that are glued together to create a ring.  The two rings of twelve triangular pyramids are interlocked to form a cube. 

Here is the PDF.   I used 65 lb. cardstock. 

https://drive.google.com/file/d/1qTpHFvwx4Ul_LNnqEO35ttPd3dZkA89C/view?usp=sharing

Here is the .Studio file. 

https://drive.google.com/file/d/18j_Qb3Awri6EvuN4asVqaWMiGZUXZDyK/view?usp=sharing

Here is the SVG.

https://drive.google.com/file/d/1BHrhI55HCbprxDMOCD5SHOpjvcNB9GdM/view?usp=sharing

To Make Yoshimoto's Cube #2

Make a box to contain the cube.

Cut four of the above pieces. Orient the piece as shown with the large tab on the right. Valley and mountain fold the dotted lines like an accordion. This piece creates six triangular pyramids. I recommend making all four sections together as an assembly line as the instructions are the same.

Mountain fold all the remaining dotted lines except the large tab on the right.

Turn the piece over with the large tab on the right.

1. Apply glue to the two tabs as shown above.

2. Adhere the bottom tab to the center of the diamond.

3. Adhere the top tab to the inside of the triangular pyramid.

4. Apply glue to the two tabs as shown above.

5. Adhere the bottom triangle to create another triangular pyramid. 

Repeat the above five steps until you get to the last triangular pyramid where the last tab is should not be glued. 

Fold the small tab inward and adhere the other two sides of the triangle. There is an opening at the base of one triangle for the large tab to be inserted later to create the ring.

Completed segment.

Glue both sides of the large tab and insert into the opening of the other segment.

Apply glue to both sides of the large tab and insert into the other side of the segment to complete the ring.

Repeat gluing the other ring together.

Push the lower six triangular pyramids together.

Flex the top and bottom triangles upward to create a square base. Place in a box.

Repeat for the other ring to make two parts of the cube.

Interlock them to create the cube.

Please check out my other blog postings for Yoshimoto's Cube #1

https://papercraftetc.blogspot.com/2021/07/a-stem-project-yoshimotos-cube-1-two.html 

and Yoshimoto's Cube #3.

https://papercraftetc.blogspot.com/2021/06/a-stem-project-ring-of-twelve-flexible.html