Making Maths

This is the Broken Square Cube by David Mitchell Folding instructions are here . This doesn't feel as though it is going to hold together well until the last piece goes in.  Now it is pretty stable. Folded from 6 squares of paper.  Blue on one side, white on the other.

This is a nice one.  Kusudama Starsea by Tomoko Fuse Video instructions here  https://www.youtube.com/watch?v=u-71U6rs9Vg There is even this video  here  that puts a light inside and makes it a lamp.  Looks nice.