I spent last weekend in Philly.  While I was there, I made it a point
to check out the Hacktory (
http://thehacktory.org ).  Walt was a
gracious host, and we spent a lot of time playing with the fab@home
machine (
http://fabathome.org ).  I highly recommend you visit if you
have the chance.  If nothing else, it's hypnotic to see the 3d printer
in action.
Nick