Profiled at Ars Technica is the (mostly) 3D-printed semi-auto pistol design from a West Virginia maker known as Derwood. The PLA-based design, which Derwood calls the Shuty MP-1, isn't quite all-plastic; like others that are roughly similar, it utilizes metal for a few parts that aren't practical in plastic. (Ars says just the barrel and springs, but it looks like metal is used for the guide rod and an internal plate, as well as for the screws that hold the whole thing together.) The core of the gun is a lower that bears a strong resemblance to an AR-15's, but the assembled gun looks to me more like a Skorpion submachine gun. Unlike Cody Wilson's single-shot Liberator pistol (mentioned here a few times before), the design files are not available for download -- at least not yet: "Not long," Derwood writes in a comment on a YouTube video of the pistol's assembly.