This is a talk I gave at the 2021 SIAM Mathematical Aspects of Materials Science conference. It’s about our paper with the same title, which you can read here: https://arxiv.org/abs/2101.07041 . The talk leans more in the origami direction than the paper, just because I was asked to speak at the origami-focused part of the conference. If you’re wondering why I seem to be so attached to that banana picture, it’s because it took me about 50 attempts to take it for the paper, to find just the right angle :/