You've probably seen links to this lovely video by Cristóbal Vila before, but I had trouble finding it this morning, and I'm hoping I'll find it more easily the next time if I post about it. This video inspired parts of the design of the book cover for Playing With Math: Stories from Math Circles, Homeschoolers, and Passionate Teachers. I'm hoping we'll have the book out by summer. (But I have guessed wrong so many time before, I must emphasize that this is only a hope.)
INSPIRATIONS from Cristóbal Vila on Vimeo.
Vila has written about the math in the video here.