This is a big deal. It’s been an open question whether even billiards in a triangle always has a periodic orbit. Not surprised that all polygons would fall at once, however. The methods don’t even look too intimidating. Need to study this more carefully!
Also:
Link to the book (which also has crease patterns that can be downloaded): mitani.cs.tsukuba.ac.jp/book/curved_...
From yesterday to today, I figured out how to use my Silhouette cutting machine to score the cardstock. It makes the folding so much easier!
Borromean carabiners and Borromean paper clips.
Here are a few more curved origami pieces. I've been reading _Curved-Folding Origami Design_ by Jun Mitani. The treble clef is his design. The trefoil is mine. I made the others, but they were based on photos in his book.
Two different figure-eight knots made with curved origami. The blue one has a fold angle of 90°, and the purple has a fold angle of 60°. The latter can be made with one strip of paper. The former required two.