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."

Here's a video of Derwood test-firing the gun:

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.

Despite those metal shortcuts, the Shuty's semi-automatic features represent another incremental step in the improvement of homemade weapons manufactured with digital DIY tools. And by making the weapon at home, Derwood successfully circumvented all gun control laws. Since the metal parts he purchased aren't subject to any regulation, he legally created a weapon that carries no serial number and didn't at any point require a background check or even ID.

The Shuty-MP1 isn't actually the first 3-D printed semi-automatic weapon, or even the the first "mostly 3-D printed" one. Derwood says he believes he created that first-of-its-kind firearm himself last year with an earlier version of his Shuty invention. The latest version only streamlines that earlier weapon's design to bring it closer to the shape and size of a traditional gun, to avoid a welding step that was necessary in the older version, and to improve its reliability.

Here's a video the components of the Shuty-MP1 being assembled into a working firearm:

Derwood says he was first introduced to 3-D printed firearms through a group of digital DIY gunsmiths known as FOSSCad, which has been collectively honing and sharing printable weapon designs for years. But Derwood says he won't be publishing the CAD files he used to make the Shuty-MP1; he says he built the weapon merely as an engineering challenge, not to undermine gun control laws as more political 3-D printing-focused gunsmiths like Defense Distributed have sought to do. "Some people like to build things for themselves," he says. "It's an off-the-grid type of attitude."

Despite his videos showing the Shuty-MP1's construction, Derwood says he's not worried it could be used by criminals looking for an untraceable and unregulated weapon. After about 18 shots, he says, the plastic around the gun's barrel begins to melt and deform unless it's allowed to cool. "If you keep shooting, it's going to fail," he says. "That makes it not such a desired weapon for a criminal."

Then again, Derwood says he's working on a version printed in nylon instead, which he believes would increase the weapon's tolerance for stress and heat. The march of gun-printing progress continues.