Designing gadgets with desktop 3D printers is nothing new. But until now, no one has ever used an at-home thermoplastic machine to help build a pistol. For one of the nation’s gun lobbies, it's about time.

The firearm in question is a .22-caliber rifle developed by Wisconsin engineer and amateur gunsmith Michael Guslick. Using his Stratasys 3D printing machine and blueprints downloaded from the internet, Guslick successfully printed the lower receiver — or frame — of an AR-15 rifle and turned it into a gun. He also shared the results on his blog.

"People have been making firearms at home since before America was a country," Dudley Brown, executive vice president of the National Association for Gun Rights, tells Danger Room. "And not only does it not make it dangerous, it makes America safer. It’s where most of the innovation came from. John Moses Browning built guns out of his basement. We’re still using them."

Neither Brown nor the NAGR condone building firearms illegally. But at-home plastic gun manufacturing raises some thorny legal and regulatory questions, and has some worried it could undermine attempts to keep America's guns under control. Managing the flow of solid weapons is one thing. How do you control a digital pattern that people can use to print guns in their living rooms?

Note that Guslick didn’t manufacture the entire weapon using the printer. The rest of the rifle is assembled from commercial off-the-shelf parts. Guslick provided a photo of an earlier pistol model — seen above — to Danger Room, which shows a printed thermoplastic lower receiver, and a commercially bought metal upper receiver, barrel, grip and magazine. And of course, Guslick didn’t manufacture the ammo either. But as metal and ceramic materials become available for low-end printers, it could become possible to one day print an entire gun.

Legally, however, Guslick did print a firearm. Well, maybe. Under the Gun Control Act of 1968, the receiver is what determines whether or not a gun is a gun. No receiver, no gun. For the nation’s gun lobbies — pro- and anti-gun — that may present a problem.

Michael Guslick's printed AR-15 rifle: Photo courtesy of Michael Guslick

"The laws were written assuming people could make their own guns … the law still does regulate and restrict that," Daniel Vice, senior attorney at the Washington-based Brady Center to Prevent Gun Violence, tells Danger Room. Guslick likely didn’t violate any laws surrounding the manufacturing of the gun without a license, as it’s only for personal use. If he attempted to sell the pistol, or opened up a factory producing the weapons, he’d need authorization from the government.

But Vice said the weapon could possibly be illegal under the Undetectable Firearms Act of 1988, which bans the possession and manufacturing of firearms that can pass undetected through airport security. But U.S. law is unclear whether this would apply to a gun with metal parts. The Glock pistol, for example, uses plastic parts.

The National Rifle Association did not comment by press time. A representative from the Second Amendment Foundation would not speak on the record, either.

There are also questions about the weapons' practicality, at least for now. Given another decade or two, they could become easier to build. One current problem is that an upper receiver — where the gun’s chamber is located — made of thermoplastics could melt when experiencing the heat given off by a gas-powered rifle. Building a plastic weapon at home also isn't like pressing a button, and requires a bit of technical know-how. Brown also doesn't think criminals would bother trying to make them.

"Some [firearms] are legal to make and some aren't, and it doesn't change America," Brown says. "[Aurora shooting suspect James] Holmes legally bought his AR-15. So it's not like crooks are worried about getting a hold of firearms."

But beyond that, there’s nothing technically stopping anyone from making one, or at least the receiver. One hobbyist built an AR-15 magazine. "On a technical level, this is absolutely boring, this is old news," Guslick says, surprised by the media attention he’s received. But, he says, "On a legal level, this is kind of a curiosity."

He added that he’s not worried about whether his gun breaks the law. "I don’t think it does, legally. There are commercially manufactured lowers which are pure polymer, no metal at all. So if it was an issue we would have heard about it on a commercial basis long ago."