Two-year-old Emma wanted to play with blocks, but a condition called arthrogryposis meant she couldn't move her arms. So researchers at a Delaware hospital 3D printed a durable custom exoskeleton with the tiny, lightweight parts she needed.

5-Year-Old Boy Gets Robotic Hand Made With 3-D Printer

http://www.thingiverse.com/thing:44150
http://www.thingiverse.com/thing:45433

http://enablingthefuture.org/
(although you might wonder why the photographer needs to spread his ego there)