3D Printing: The Future of Unlicensed Weapons?

In the wake of the tragic shooting in Colorado earlier this week, the Atomic forums entered a discussion on gun control and gun laws not only in Australia but the USA. Naturally as conversation progresses the topic goes off track a little, and one Atomican discovered a forum discussing the manufacture of AR15 lower receivers.
At first glance some readers, and especially gun enthusiasts may say "so what, why is this any different to making your own car parts?". Well, the answer really is very simple, an engine part is not an object designed with the specific purpose of forging a weapon, a lower receiver is for the most part, is destined for such duties.
For now, the forum user has only managed to construct a lower receiver, but from reading his post, it hasn’t taken him all that long to manufacture, and given that the serial number is usually located on the lower receiver of the AR15, it essentially makes this gun untraceable to the Police if left at the scene of a crime.
Assuming this "hobby" continues, and people create more fully functioning assault rifle parts, there is going to be a rather large increase in illegal gun ownership. The scary part is, that all you need is a 3D printer and the know-how to design your own print files, or simply download any current projects from firearm forums.