Folding and cutting spheres. Awesome symmetry balls include card constructions by George Hart, which you can learn about here (and others are on georgehart.com): http://youtu.be/YBUEYrzMijA and the Gardner Ball by Oskar van Deventer with design by Scott Kim made in honor of Martin Gardner, which you can learn about here: http://youtu.be/rVHXlltXIlI and the Wolfram rhombic hexacontahedron thingy, and others! My personal website, which you might like: http://vihart.com