FOR THE LAST three years, the evolution of firearms has been playing out all over again in plastic form: Deadly, working guns that anyone can generate with a download and a few clicks on a 3-D printer have mutated from mere individual components to a single shot pistol to a reusable rifle. Now the 3-D printed gun community is approaching the next controversial milestone in that progression of printable ordnance: a semi-automatic weapon.

Last weekend a 47-year-old West Virginia carpenter who goes by the pseudonym Derwood released the first video of what he calls the Shuty-MP1, a “mostly” 3-D printed semi-automatic firearm. Like any semi-automatic weapon, Derwood’s creation can fire an actual magazine of ammunition—in this case 9mm rounds—ejecting spent casings one by one and loading a new round into its chamber with every trigger pull. But unlike the typical steel semi-automatic rifle, Derwood says close to “95 percent” of his creation is 3-D printed in cheap PLA plastic, from its bolt to the magazine to the upper and lower receivers that make up the gun’s body. “No one had ever tried to get a semi-automatic 3-D printed gun working before…I’m just one of those types, I like to find new things that people say can’t be done,” he says. “It’s simple, but it works. The gun shoots great.”

But unlike other 3-D printed weapons that have spooked gun control advocates and raised thorny First and Second Amendment questions, the Shuty-MP1 is far from a fully printed firearm. Derwood’s “95 percent printed” description may apply to the overall material that makes up the gun. But unlike some other 3-D printed guns, he didn’t attempt to build the most complex moving parts or stress-absorbing elements from plastic; its store-bought Glock barrel, hammer, firing pin, bolts, and springs are all metal.