On request of a friend, I made a Christmas pudding tree decoration on my 3D printer. It's taken me hours to get it all right, and takes a few hours to print too. Also, its popularity has meant I've had to make a dozen of them. Still, it's kept me out of trouble for a couple of weeks!
Update 16/12/12: I just received an email saying that this got featured on the Thingiverse home page! Wow - high praise indeed!