With 3D printers dropping below the US$200 mark, the home 3D printing revolution appears to be getting into full swing, which is great … if you want to make things out of plastic. Unfortunately, the price of commercial metal 3D printers means the ability to print metal objects has remained out of reach of most people. That could be set to change with a team from Michigan Technical University building a 3D metal printer for under $1,500. http://www.appropedia.org/Open-source_metal_3-D_printer
Says the height of the print head is 7mm. Sounds pretty low res, but it’s MIG welding so it could be laying down a thinner layer at the tip of the electrode.
I’ve TIG welded a tiny bit before, the metal’s got to be super hot to melt into a bead. The parts swell considerably when they reach welding temps. Once a bead is laid, and the protective gas curtain is removed, the metal oxidizes. In order to lay another bead on top, I’m pretty sure you’d need to clean the surface of the previous layer. I suppose the whole thing could be performed in a box of inert gas.