Shape Deposition Manufacturing
It's called Shape Deposition Manufacturing. (At least by some people.)
Here's a Stanford Lab that's done a lot of work on it.
It's a very cool subject which we'd be very happy to have under the RepRap umbrella. It would mean lots of tiny gears, or gears which mesh nicely etc.
Here is a google scholar search on "shape deposition manufacturing" http://scholar.google.ca/scholar?q=shape+deposition+manufacturing&hl=en&btnG=Search&as_sdt=2001&as_sdtp=on
Let me know if you guys want me to give SDM its own forum.