You know what it's like when something catches your attention and suddenly it seems you're seeing that thing everywhere. It's been like that for me lately with the Magic Square. What's magic about it? Well you start off with an odd number of stitches and do a double decrease in every second row . . . and hey presto--it turns into a square.
Now for the geometry. I figure if you can make a square, then you can make a cube. So I had a go at designing a helmet: Two squares for the sides, a square for the top and one for the back and a rib band at the neck. I think it needs a band around the front as well and the wool is rather uninspiring, but it was fun working it out.