The concern has led to the point where Wilson had to return his 3D printer to the manufacturer who feared that something illegal was going on. So far, only parts of guns and rifles can be printed and even those parts may not become serious weaponry anytime soon. In a review posted on the WikiWep DevBlog, a group of testers downloaded only the lower receiver of an AR-15 automatic rifle, and showed that the printed part was strong enough to endure a total of six shots, which was shorter than the expected ability to last for about 20 shots.
The forces created by the shots apparently exceeded the plastic's capability by a significant margin: "It seems like the off-axis force generated by recoil simply "popped" the whole ring area off the receiver in the area of the receiver tube anti-rotation plate," the blog entry reads. Of course, some may argue that the rifle lasted for six fired shots is six shots too many for gun that can be printed from files that are freely available on the Internet. Wilson himself claims that the Wiki Weapon could go into testing by the end of this year.
Source: Toms Hardware | Printable Gun