[math-fun] Folding a tie in thirds

James Tanton's video https://m.youtube.com/watch?v=G8cD5NMOMcs is fun but I don't plan to adopt his solution; when I have to fold a tie into thirds, I use several fingers plus a little physics to equalize the lengths. It's hard to describe; a little bit like pulleys. (I guess I could make a video clip if any of you are unsure of what I mean.) But the open-ended ending of Tanton's video makes me wonder how my physics-based approach could be generalized to other folding fractions. Surely someone has written about this? Also: my method ignores the fact that fingers have positive radius. I wonder if some variant of my method compensates for this. Jim Propp