Luigi Mangione Allegedly Had a 3D-Printed Gun. Why Are They Legal?
This story was originally published by The Trace, a nonprofit newsroom covering gun violence. Subscribe to its newsletters.
For decades, weapons manufacturing has been the domain of arms industry heavyweights: Glock, Sig Sauer, Remington, Sturm, Ruger & Co. Making a gun from scratch at home required thousands of dollars of machining equipment and years of engineering expertise.
But that has begun to change. Advancements in 3D-printing technology have yielded increasingly reliable 3D-printed firearms, many of which require no federally regulated components to function.
In recent years, crimes involving ghost guns seem to have abated across much of the United States. Ghost gun recoveries by police in New York City, Los Angeles, Philadelphia, Baltimore, and other major cities dropped by as much as 25 percent between 2022 and 2023, and the most prolific maker of the kits used to build the untraceable weapons closed its doors this year. The likely cause is a federal rule change requiring the kits to be serialized — a stipulation that forces sellers to conduct background checks on their customers.
Still, the guns continue to make headlines: In December, Luigi Mangione, the man accused of fatally shooting UnitedHealthcare CEO Brian Thompson, was apprehended with a partially 3D-printed pistol that police allege he used in the killing.
Below, The Trace breaks down the basics of plastic, 3D-printed firearms, and the controversy generated by the swelling movement to deliver them to the masses.
What is a 3D-printed gun?
In the simplest terms, it’s any firearm that includes components manufactured with a 3D printer.
But 3D-printed guns vary a lot. Some models — like the 3D-printed gun company Defense Distributed’s “Liberator” — can be made almost entirely on a 3D printer. Others require many additional parts, which are often metal. For example, many 3D-printed gun blueprints focus on a weapon’s lower receiver, which is basically the chassis of a firearm. Under federal law, it’s the only gun part that requires a federal background check to purchase from a licensed dealer. To subvert regulators, some people print lower receivers at home and finish their guns using parts that can be purchased without a background check — metal barrels, for example, or factory buttstocks.
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Advances in printing technology have driven the price of 3D printers down — they’re now around $200 on Amazon — and gun groups offer guides for getting started. These developments have lowered the barriers to entry for those in search of untraceable guns.
The process still remains more involved than most methods of obtaining a firearm, though. For instance, 3D printers require meticulous setup — the component that extrudes plastic must be calibrated, software must be downloaded to convert designs into 3D-printable slices, and the printer must undergo a slew of upgrades to reliably print weapons parts, which themselves require precise construction to ensure they can contain the explosion from a gunshot.
Why are they a big deal?
Because 3D-printed guns are made outside traditional supply chains, and don’t require background checks, they’re effectively invisible to law enforcement agencies. They are a form of ghost gun: unserialized, and unable to be traced if recovered by law enforcement.
There isn’t good data on the number of 3D-printed firearms that have turned up at crime scenes, though state attorneys general opposed to the technology insist that some have been recovered. On a few occasions, crimes involving the guns have made headlines. In February 2019, police arrested a Texas man after he was found test-firing a 3D-printed gun in the woods. He was prohibited from purchasing firearms and had a hit list of lawmakers on him.
Of particular concern to many law enforcement agencies are guns that can be completely 3D-printed at home without metal components. Politicians and law enforcement professionals fear that such guns would be able to evade metal detectors, and thus slip into places where firearms are prohibited, like airports or government buildings. At present, these fears are largely unfounded — 3D-printed gun designers have yet to develop an alternative to metal bullets, and security officials say that X-ray detection in place alongside most metal detectors can identify the outline of 3D-printed firearms with ease. Indeed, Transportation Security Administration officers have seized 3D-printed firearms at airports on several occasions.
Still, the weapons’ lack of traceability has already caught the attention of terror groups, according to Mary McCord, a former U.S. attorney and prosecutor in the Department of Justice’s National Security Division. “We know from a counterterrorism perspective that there’s great interest among terrorist organizations in being able to have workable, usable, efficient, functioning 3D-printed weapons.”
Is it legal to make a gun using a 3D printer?
In most cases, yes. Federal law permits the unlicensed manufacture of firearms, including those made using a 3D printer, as long as they include metal components.
In the absence of federal regulation, a handful of states have taken their own steps to clamp down on the creation of homemade guns. In California, anybody manufacturing a firearm is legally required to obtain a serial number for the gun from the state, regardless of how it’s made. In New Jersey, you are supposed to obtain a federal manufacturing license before 3D-printing a gun. The state also criminalizes the manufacture, sale, or possession of undetectable firearms, and made it illegal to purchase parts to make an unserialized gun.
What about sharing the blueprints online?
The legality of sharing the files required to print guns and gun components is murkier territory. No federal legislation bans the practice. But in 2013, the State Department ruled that releasing blueprints online violated arms export laws. In 2018, after a lengthy court battle with Defense Distributed over the guidance, the State Department settled, and agreed to permit the files’ release. But before the prohibition was lifted, a coalition of states sued to keep it in place — and won. Now, gun groups intent on sharing the files online have exploited a loophole in the State Department’s policy, which allows for the distribution of blueprints exclusively to U.S. residents. Defense Distributed maintains it has established a vetting procedure to ensure only U.S. residents are able to download them.
The Trump administration transferred oversight of gun exports from the State Department to the Commerce Department in 2019. The change requires people interested in publishing 3D-printed gun blueprints to obtain a special license.
That same year, after New Jersey’s then-attorney general, Gurbir Grewal, sought an injunction to block Defense Distributed from releasing files to his state’s residents, the company countersued. It alleges that the blueprint files are a form of speech, and that Grewal’s effort to block their release violates the First Amendment. A federal judge dismissed the countersuit, but Defense Distributed has appealed.
Who is printing guns — and why?
The first 3D-printed firearm to make a splash in the popular consciousness was the “Liberator” — a near fully plastic gun designed by a self-described anarchist and ghost-gun advocate named Cody Wilson. (Designs for the Liberator call for a small steel block to be sealed inside the plastic in order to comply with federal law.) Wilson founded Defense Distributed to advance and share the technology, and has initiated many of the group’s highest profile legal battles. In 2019, Wilson was sentenced to probation and ordered to register as a sex offender after soliciting sex from a minor.
Though Wilson’s is the best-known and formally recognized gun printing “company,” the practice is mostly advanced by informal collectives across the internet. These groups, like Deterrence Dispensed and Fosscad, gather anonymously in chat rooms and on social media platforms to crowdsource the development of new gun designs and spread them across the web. They have thousands of members, but remain mostly decentralized, making it difficult for technology companies or law enforcement agencies to police them.
Proponents of the technology fall into several different camps. Some, like Mustafa Kamil, a creator of 3D-printable guns based in Romania, think that concerns over homemade weapons are overblown. Gun printing, he says, is mostly the domain of hobbyists like himself: technical experts interested in tinkering and engineering. To 3D-print a gun, “you need to have enough money to buy a printer. Then you need enough expertise and experience to know how to use the printer. If your axis is off by 0.15 millimeters the gun isn’t going to work,” he said. “To buy a black market firearm would be much easier.” Kamil said he’s owned 32 printers and completed two apprenticeships with gun manufacturers.
Others see the potential for armed conflict with the government as the driving force behind their creations. Members of Deterrence Dispensed and Defense Distributed have fashioned a brand out of this perceived threat, adopting popular Second Amendment slogans like “Come and Take It,” “Live Free or Die,” and “Free Men Don’t Ask.” Leaders of the groups share a deep conviction that gun ownership is the only way to ensure freedom: In an interview with Popular Front, a conflict journalism outfit, the founder of Deterrence Dispensed — a man who went by the username jstark — continuously pointed to the threat of government tyranny as a justification for creating 3D-printed guns and distributing their blueprints. “Just look at the Uighurs in China,” he said, referring to the ongoing genocide of the ethnic minority. “Just look what’s happening to them. No one’s helping them. Nobody does shit. You know what would help them? If they were armed. That would be a deterrence.”
To jstark, identical threats existed anywhere where civilians were largely unarmed, including in Europe, where he lived. When asked if he would fight police who tried to confiscate his guns, he was frank: “Basically, yes. Live free, or die. These are not empty words.”
Jstark died in 2021.
Are these groups aligned with extremists?
While politicians and law enforcement agencies have dubbed the advocates of 3D-printed firearms extremists, the movement has no unifying political ideology. Jstark, for his part, said in the Popular Front interview that Deterrence Dispensed had no tolerance for people who wish to harm others: “If they do show through [their actions] that they’re extremists, racists, islamic terrorists — then we would kick them out immediately,” he said. He did not respond to multiple requests for comment.
The alarmism about about looming government tyranny has attracted groups eager to ignite government conflict, particularly in the U.S. Members of groups connected to the boogaloo, a loose-knit coalition of anti-government extremists that advocates a violent civil war, have seen 3D-printed gun advocates as allies in an overlapping struggle.
In 2020, Deterrence Dispensed released blueprints for a printable auto sear — a component that can be used to turn a semiautomatic rifle into an illegal, fully automatic firearm — called the “Yankee Boogle,” an apparent boogaloo reference. Later that same year, two boogaloo adherents were charged for allegedly attempting to sell auto sears to representatives of Hamas, the Islamist extremist group. In court documents, prosecutors alleged that one of the defendants in that case said he obtained the auto sears from a supplier who 3D-printed them.
In a separate case, federal prosecutors charged a man from West Virginia with 3D-printing auto sears and selling more than 600 of them online, including to several boogaloo adherents. One man who bought the 3D-printed auto sears is accused of killing a police officer and a security guard in California. It is unclear if any of the auto sears used in these crimes were designed by Deterrence Dispensed.