On the face of it, it’s hard to imagine two things as unrelated as mathematics and knitting. And yet, here we have a website devoted to mathematical knitting:
A Klein-bottle hat (seen at right)? A Mobius scarf? Ingenious stuff, and a testament to our unlimited creativity and resourcefulness, if not our practicality.
The Klein bottle hat actually reminds me of the Klein bottle one of my students made out of plaster.