I wanted some sort of smart title like Young Einstein, but that was taken. And this Instructable is less about physics and more about math.
This is a great way to introduce young kids to geometry without them knowing about it. Lots of kids get stuffed baseballs, footballs, and soccer balls. They all have interesting shapes and designs. The soccer ball is recognized as a truncated icosahedron, but no one is selling the other great polyhedron, like octahedrons, pentagonal hexecohedrons, and rhombic dodecahedrons.
Here we'll make a pattern for our polyhedron and then sew it together with scrap material.
(Pictured is the finished rhombic dodecahedron.)
Step 1: Get Polyhedron Net
The polyhedron net is a spread out 2D version of the 3D polyhedron. It is like the un-folded version of the polyhedron.
The best source of polyhedron nets that I've found is from Wolfram MathWorld.
(If the link doesn't work follow from www.mathworld.wolfram.com through Recreational Mathematics --> Mathematical Art --> Polyhedron Nets.)
Select the "Build your own polyhedron" button.
Print two (2) copies
-one at normal scale
-one at larger scale for pattern
(The larger the pattern, the easier it will be to sew together. I upscaled my printout to 300%.)
Most of the polyhedron use regular polygons in the nets. The attached PDF file has a set of polygons that you can use for your templates.
Step 2: Make Paper Model
It is important to build a paper model so it is easier to see how the fabric pieces will fit together.
Cut out the normal size polyhedron net.
Fold together and tape with transparent tape
Step 3: Make Face Pattern
Cut out the face pattern from the large scale printout.
The rhombic dodecahedron has 12 of the same polygons for the faces, so I only had to create one pattern.
I cut out the paper shape. Then I transfered it to the cardboard from an old Diet Coke case. I've found it is easier to mark fabric from a cardboard pattern than from a paper pattern.
Step 4: Gather Materials
This is a great project for any left over scrap material. The amount needed will depend on the polyhedron that you picked from MathWorld.
You'll also need some Fiber Fill for the stuffing.
Step 5: Sew Together Inside-Out
Sew together each of the faces with the good side of the fabric facing the inside. Use your paper model to review the correct order of the faces. Leave the last edge open.
Step 6: Stuff Polyhedron
Fold the polyhedron right-side out through the edge that was left open. Use fiber fill to stuff the polyhedron. Be sure to press the fill into all of the corners. Some polyhedron will have sharp corners that will be harder to fill.
Step 7: Finish Stuffed Polyhedron
Finish stuffing the polyhedron. Stitch the open edge together. Here I use a simple whip stitch to finish it off.
Once it is finished, give this toy to a young child. They will play with it like other stuffed toys, but will grow comfortable with complex 3D geometries long before they see them again in school.
There are lots of polyhedron nets available from MathWorld. Try a few of the different polyhderon to use up more of your left over scrap material and grow a young mind.