[SmokeyHamster]

This was posted before. Not really 3d printing. It's more of a quick casted mold maker, since it just uses a conventional CNC machine to "draw" the shape in sand and then it pours molten metal in the sand mold.

A clever enough idea, but the results are mixed. It's limited to fairly simple 2d shapes and the quality of the "prints" are quite poor and require a lot more post processing than true 3d metal printers.