Cody Wilson and his nonprofit Texas organization, Defense Distributed, uses 3D printing technology. He just released a video that showcases one of his guns firing off more than 600 rounds, which demonstrates a new surge of interest in semi-automatic and automatic weapons that are made using the additive manufacturing process. Just last year, his organization demonstrated that they could use a 3D-printed “lower” for an AR-15 (the civilian version of the military M16 rifle) semi-automatic rifle, but it failed to work after just six rounds. Now, with some reworking, they’ve shown that they’ve fixed the design flaw. So the lower, or “lower recover” is the part that contains all of the gun’s operating parts, including its trigger group and the magazine port, and the AR is designed to be modular, which means it can have different types of barrels or “uppers, and different-sized magazines. According to Wilson, more than 10,000 people have already downloaded the lower CAD file. Currently, it’s legal to manufacture a 3D printed gun, but if a person is a firearms manufacturer, they must have a manufacturing license.