Make a dodecahedron from A4 paper!
Did you know it's possible to build a dodecahedron using only 12 sheets of A4 paper?
The unique 1:√2 ratio of the page means that you can get very close to (although not exactly) a 108° angle by folding the corners into the centre, and then construct a regular pentagon - with tabs on two of the sides, and slots on two others. 12 of these will build into what we affectionately call the "faux-decahedron", without any glue or tape (although you can use some if you're struggling!) and the tabs will hold the pieces together.
It's a great activity for developing 3D spatial awareness, hand-eye coordination, following instructions and working in a team - and it produces fantastic displays!