Personal

Icosahedron

Here's something I've not done in a long while: make a model Platonic solid.

I suspect we were pretty much the only family for which mathematical model making was a regular weekend activity. I vaguely remember the dodecahedron being my favourite thirty years ago - probably because it sounded like a dinosaur.

Throughout the intervening years I've had no reason to make myself an icosahedron, but today - while playing around with some 3D computer graphics - I finally found the need. (The icosahedron is a good approximation of a sphere, especially if you further subdivide the faces. And when creating software models there's nothing like having the real thing in your hand to help.)

It was harder than I though - presumably because my fingers were somewhat more slender back then. I think I'll hang on to this one; I don't much fancy trying to repeat the trick in another thirty years' time.