This is a three-dimensional Union Jack.

After some light sanding the parts will fit together very snugly, without any need for glue.

I've colored this one with Sharpie brand permanent marker, which appears to work well and not transfer to the white parts of the model too much.

© 1998, 2009 Matt Chisholm; All rights reserved.

This is a puzzle proof of the Pythagorean theorem starting from triangles instead of squares. The puzzle is actually quite difficult.

Inspired by Magic's puzzle: http://www.shapeways.com/model/26231/pythagoras_puzzle__small_.html