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 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
Cut out the normal size polyhedron net.
Fold together and tape with transparent tape
Step 3: Make Face Pattern
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
You'll also need some Fiber Fill for the stuffing.
Step 5: Sew Together Inside-Out
Step 6: Stuff Polyhedron
Step 7: Finish Stuffed Polyhedron
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.