The Tiling Database. Browse some random patterns. Or narrow down your search here.
Looking for an ornament in the Alhambra? Or a spiral tiling? Or perhaps a Topkapi scroll?
posted by vacapinta on Jan 13, 2009 - 10 comments

Jim Loy's Mathematics Page is (among other things) a collection of interesting theorems (like Napoleon's Triangle theorem), thoughtful discussions of both simple and complex math, and geometric constructions (my personal favorite); the latter of which contains surprisingly-complex discussions on the trisection of angles, or the drawing of regular pentagons.

Similarly enthralling are the pages on Billiards (and the physics of), Astronomy (and the savants of), and Physics (and the Phlogiston Theory of), all of which are rife with illustrations and diagrams. See the homepage for much more.

If you like your geometric constructions big, try Zef Damen's Crop Circle Reconstructions.
posted by odinsdream on Sep 14, 2005 - 8 comments

Astonishing geometric art using only folded paper plates, from Bradford Hansen-Smith at wholemovement. View the gallery of fantastic polyhedral creations, and learn how to do it yourself. (For more fun with paper plates, see also Paper Plate Education: Serving the Universe on a Paper Plate.)
posted by taz on Oct 27, 2003 - 7 comments

Ton Mondrian Is Even Worse Than Mon Mondrian: Use the machine to see how you square up to the Master. [Shockwave required; first link via Bifurcated Rivets.]
posted by MiguelCardoso on Jan 23, 2003 - 18 comments