Spotted in the MAKE Flickr Pool, this 3D printed set of chassis components from user nathanmatsuda:

So far I've made end panels for the duemilanove and the ethernet shield. Next up- a new top piece that'll have an opening for the prototyping shield. Also planning a top piece for the touch shield (but I don't have one of those yet).

The parts are available in his Shapeways shop.

Article from: http://blog.makezine.com/archive/2010/07/modular_stackable_arduino_enclosure.html