I suppose it was inevitable, in a good way. Some friends of freedom have begun a project dedicated to developing and sharing open-source designs for firearms that can be manufactured with a 3D printer. Read about it here at Defense Distributed.
I approve, of course. I approve of any development that makes it more difficult for governments and criminals to monopolize the use of force. As 3D printers become less expensive and more ubiquitous, this could be a major step in the right direction.