Zhoubi Bowl, by Philip Chapman-Bell
For this week, we've got a nice, deceptively simple bowl from Philip (you might know him as oschene on Flickr). I say deceptively simple because although it's not too hard to fold, the math behind it is fascinating, and surprisingly complex, when it gets down to it. There's a division by sevenths in there, and even an allusion to a proof for the Pythagorean Theorem from an old Chinese mathematical text.
Diagrams available here.