I was involved a while back in an aerospace engineering program where we needed prototype parts, and we went to a rapid prototyping firm who made our parts using stereo lithography (the technology being discussed). We got into a conversation about how this technology would progress, and the engineers came to the conclusion that in the future we would each have a household appliance about the size of an oven. When you wanted a (watch, camera, stereo, pistol, lamp, toaster, etc) you would make an online order, and then go to your "machine" an hour later and find that it had grown there... NASA is going to be one of the technology leaders in this. Imagine the ability of a long duration spacecraft to not need to carry repair parts, just data files and a machine...
Laugh now, it'll come true before you know it.