Self-replicating 3D printers could help build settlements on the Moon

What’s the most useful thing a 3D printer could print? Metal automobile or aerospace parts? A concrete building? Medical supplies? Even more useful would be something that would produce all of those things and more, on its own: a 3D printed 3D printer. Researchers in Canada have been looking into the possibility of making a 3D printer that could replicate itself in its entirety, which could potentially be used to build settlements in space ready for the arrival of humans (as well as other structures).

from 3ders.org - http://www.3ders.org