Sturdiness, however, isn't typically the first thing that comes to mind when talking about 3D-printed items. The first few iterations of both the AR-15 receiver and the Liberator failed after squeezing off just a few rounds. Getting them to stand up to the rigors of repeated use has required a lot of trial and error. From the image above, the group has obviously cleared that hurdle with the CM109 components (at least for the first few seconds of rapid firing). "It has been fired with little to no issues," the group said in a statement. Reportedly, the CM109 team crafted the component using a commercially available $500 DaVinci 3D printer.