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In late 2024, federal law enforcement officials are celebrating a big year in the fight against homemade, untraceable "ghost guns."
The number of ghost guns found at crime scenes is declining in cities across the country. The Supreme Court appears poised to uphold a de facto federal ban on kits used to assemble weapons. Polymer80, once the largest manufacturer of such kits in the country, was also forced to close.
Then, in December, a 26-year-old man allegedly used a 3D-printed ghost gun to fatally shoot UnitedHealthcare CEO Brian Thompson on a Manhattan street.
The assassination shocked the public. While this doesn't necessarily indicate that untraceable weapons are becoming more common, it does raise questions about the state of the ghost gun market. Does Polymer80's closure indicate that the market is shrinking, or is it sprouting new heads like a hydra?
Law enforcement officials, small arms researchers and ghost gun manufacturers who recently spoke to The Trace said enforcement results against ghost guns have been meager at best, especially given the Trump administration's aversion to new regulations. They warn that ghost gun technology will only become more sophisticated, making the weapons increasingly attractive to criminals.
Changing market
In the vast majority of the country, owning ghost guns is perfectly legal, but selling them is not. Companies like Polymer80 get around this ban by selling kits that contain all the components needed to build an unserialized gun: barrel, trigger, unfinished frame (also called an "80%" receiver), and all the necessary Pins and screws. Because the kits are not initially considered firearms, customers can purchase them without background checks and then assemble their ghost guns at home.
Police seized more than 92,000 ghost guns between 2017 and 2023, the vast majority of which were assembled from kits, according to data released in January by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). Kids bought the kits and then accidentally shot themselves. Mass shooters use them to kill office workers and classmates.
The violence prompted the Biden administration to crack down. In 2022, the ATF issued a rule that effectively reinterpreted the federal legal definition of the term “firearm” to cover most ghost gun kits. To sell these kits, retailers need to apply for a federal firearms license, serialize the product and conduct a background check on each sale. ATF data shows that the number of ghost guns seized by police will increase by less than 1% annually through 2023, the smallest increase in seven years.
We checked the websites of 12 online retailers known for offering ghost gun kits and found that at least 4 continue to sell these products. The Trace showed these lists to former ATF firearms expert Rick Vasquez. He said while the four retailers may have violated the new rules, selling the kits fell into a legal gray area while the rules were being considered by the Supreme Court.
Other companies responded to the new regulations by overhauling their operations. Defense Distributed — the ghost gun maker founded by Cody Wilson, the inventor of the first fully 3D printed gun — has refocused on selling desktop machines that can turn blocks of aluminum or steel into finished gun frames . Wilson first released a version of the machine more than a decade ago.
Wilson says his business is nowhere near the size of behemoth Polymer80, but he sees his machine as a step toward a more populist future in which gun ownership is beyond the control of governments and big corporations.
"I think some of what happens in 3D Guns is disgusting, but it's part of popular politics," Wilson said. "There's a defiance or a challenge to the government: Can you really control the flow of weapons?"
3D printed guns largely unaffected
In the world of 3D printed guns, the ATF’s rule changes caused little fanfare. Unlike ghost gun kits, which can be regulated at the point of sale, 3D-printed guns are often completely homemade, using parts from hardware stores and the plastic filament used in Lego bricks. The price of printers used to make guns has dropped in recent years and can now be purchased on Amazon for as little as $200.
3D printed guns don’t turn up at crime scenes nearly as often as ghost guns made from Polymer 80-style kits, but they’ve turned up in several high-profile cases.
In 2022, authorities investigating racially motivated violent extremism among current and former National Guard members in Ohio discovered evidence of a 3D-printed gun-making operation as well as bomb-making materials at the home of a former guard. That same year, a Green Bay, Wisconsin, man who was arrested for exchanging 3D-printed guns for methamphetamine pleaded guilty to federal firearms possession charges. ATF discovered a gun manufacturing facility in his basement that included 3D printers, homemade gun parts and silencers.
Last year, a team of Swiss and Canadian small arms researchers analyzed more than 180 media and law enforcement reports on the use of 3D printed guns in crimes around the world. They found only eight cases of 3D-printed guns actually being fired.
Stefan Schaufelbühl, the study's lead author, said the use of 3D-printed guns in crimes was "quite rare" compared to traditional guns. Still, he said his research highlights criminals' growing interest in homemade weapons, which he expects will grow.
"We now have to admit that it may indeed be easier (and cheaper) to buy a 3D printer and produce guns in many parts of the world," Schaufelbühl said in an email.
Schaufelbühl pointed to several models of partially 3D-printed guns that come with very detailed buying guides for the parts without attracting scrutiny from law enforcement. He said guns are becoming more reliable - a major concern for law enforcement.
As governments grapple with how best to restrict this underground industry, some in the 3D printing community have come up with their own solutions to preventing the use of their machines to make guns.
Print&Go, a Spanish company that produces business software for remotely managing 3D printers, launched a program called 3D GUN'T in November 2024. It allows administrators to preemptively block devices from printing guns or gun parts. Opting in is voluntary, but when the program launches, it checks each print job against a database of known 3D gun blueprints and uses artificial intelligence to identify the shapes of common gun parts. If the system detects a firearm, the print job will be blocked.
"For example, we work in schools where many students have access to these machines, but only a few teachers are able to monitor their use," said John Amin, the company's founder. “They needed a solution that would help them ensure that no one was printing something that could be harmful to others.”
What will Trump do?
President Donald Trump has resisted pressure to regulate 3D-printed guns during his first four years in office. This term, he promised to appoint a pro-gun ATF director to review the agency's previous rulings.
This puts the ATF's "ghost gun" reign in the spotlight. The Supreme Court is weighing the legality of the rule and is expected to rule early this year. During oral arguments in October, the justices indicated they would likely uphold the rule. But experts expect the Trump administration to reconsider the approach — a common practice during presidential transitions — which could prompt a court to uphold its decision. The outcome could reinvigorate the gear industry and fuel a resurgence in ghost gun-related crime.
Felipe Rodriguez, a criminal justice professor at John Jay College and a retired New York City police detective, said the consequences are almost certainly fatal, providing banned buyers a way to quietly arm themselves.
"The reason people get ghost guns is they can't legally get (traditional guns)," Rodriguez said, "because they can't pass a background check."