This model dates back to when I was experimenting with curved creases. A very simple model is to make alternating creases in concentric circles, and cut out the center of the paper. To me, it’s such a simple thing, but I’ve heard a lot of people really like this one.
If you like this one, check out the sculptures of Erik Demaine!
If I recall correctly, I originally got the idea from Erik Demaine in the first place. He has a course in mathematical origami, and videos of the lectures can be found online. I recall him talking about the square hypar–made from nested square creases rather than circular creases. The interesting thing about a hypar is that it’s impossible with mathematically ideal paper. That means that a real hypar must involve additional creases, or stretching the paper.
For a circular hypar? Nobody knows if it’s possible or not.