3d Metal Printer

A just-for-fun-idea (at least until I build a much less ambitious project like a [CNC machine] or plotter.

The two metals I would want to be able to work with are aluminum and steel.

Aluminum wire is pretty cheap and not a lot of special supplies are needed for arc welding. It may be possible to feed a wire in to deposit a weld bead. If this were done in a near vacuum, it should come out pretty clean. It looks like TIG welding is closes to what I need. Possible a pure nitrogen atmosphere at near vacuum would work.

http://www.appropedia.org/Open-source_metal_3-D_printer

One potential problem with this is the "puddle". The surface tension of the melted material will determine the geometry, and there may be lower limit to this because below that limit, the material will fail to transfer from the source (wire) to the destination (print). A very complex option that would allow for incredible precision would be deposition. The print would happen in a vacuum chamber. The metal would be vaporized in the print head and the plasma would be given a powerful charge. A nozzle (ideally, adjustable, but that may be difficult because it needs to stand up to extreme heat) would direct the plasma to the print, which is 'ground'. As the plasma contacts the surface, it should cool and condense.