For decades, making an untraceable firearm required specialized tools, technical expertise and hours of work.

Today, it can start with a downloaded file and a consumer-grade 3D printer.

As advances in additive manufacturing, commonly known as 3D printing, make it easier to produce firearms at home, lawmakers in a growing number of states are pursuing new restrictions specifically for 3D-printed guns. That rapidly evolving category of weapons can be manufactured from digital blueprints and often lack serial numbers used by law enforcement to trace firearms.

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This year, Colorado, Maine, New Jersey, New York, Virginia and Washington state enacted laws tightening rules around 3D-printed guns and firearms without serial numbers. The new laws include restrictions on manufacturing untraceable firearms, limits on the distribution of digital gun-design files, and requirements aimed at preventing the use of 3D printers to produce gun parts.

California lawmakers are considering a measure requiring 3D printers to include firearm-blocking technology. A Minnesota proposal to regulate 3D-printed firearms did not advance out of the legislature.

The push has been concentrated largely in Democratic-led states, though 3D-printed and other firearms without serial numbers concern some Republicans as well. Police and prosecutors have increasingly warned that such weapons can complicate criminal investigations and make it harder to trace firearms recovered at crime scenes.

The proposals also enter a legal landscape shaped by recent U.S. Supreme Court decisions that have expanded Second Amendment protections and prompted challenges to numerous state firearm restrictions. Gun rights groups have already sued over some state efforts to regulate “ghost guns” and the online distribution of firearm-design files.

Ghost guns are typically built from DIY kits or produced using a 3D printer, and often lack serial numbers required for tracking. Ghost guns can also bypass the usual background checks and other state requirements for firearm purchases and transfers.

In addition to opposing the laws on Second Amendment grounds, some gun rights advocates argue that restrictions on 3D-printed guns violate free speech protections by limiting the spread of digital information.

State measures

Maine enacted a law in January that prohibits the sale of guns without serial numbers and requires such numbers on all privately manufactured firearms, including 3D-printed guns. New Jersey’s new law prohibits unlicensed individuals from possessing digital instructions used to 3D-print firearms.

In Colorado, Democratic Governor Jared Polis signed a law in May expanding the state’s restrictions on firearms without serial numbers. The new law prohibits using 3D printers and similar manufacturing technologies to make firearms, unfinished gun parts, large-capacity magazines and rapid-fire devices.

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Washington Democratic Governor Bob Ferguson signed a similar law in March. It prohibits the use of 3D printers and computer numerical control, or CNC, milling machines to manufacture certain firearms and machine-gun conversion devices. The law also targets the digital files used to create the weapons.

In April, Virginia Democratic Governor Abigail Spanberger signed a law prohibiting the manufacture, sale or possession of unserialized firearms, including unfinished frames or receivers.

Other states have sought to regulate the 3D printers before they’re sold.

As part of New York’s state budget approved this year, a new law will require 3D printers sold in the state to include blocking technology, if a state working group determines it to be technologically feasible, that prevents the production of firearms and illegal gun parts. Violating the law would carry a civil penalty with a $5,000 fine per product.

California lawmakers are considering a similar proposal. The measure, which passed the Assembly and is pending in the Senate, would require consumer 3D printers sold in the state to include technology capable of detecting and blocking attempts to print firearms, gun parts and machine-gun conversion devices. The proposal also would require that the California Department of Justice publicly release performance and technology standards by 2028.

In Minnesota, lawmakers considered legislation that would have banned the sale and possession of ghost guns, limited 3D printing of firearms, prohibited the distribution of firearm design files and imposed additional requirements on serial numbers. The proposal failed to advance before lawmakers adjourned in May.

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The latest wave of legislation builds on actions already taken in states such as Delaware, Hawaii, New Jersey, Oregon and Rhode Island, which have enacted some of the nation’s strongest restrictions on unserialized and 3D-printed firearms.

Including this year’s measures, at least 16 states have regulations in place for ghost guns, and at least eight states and the District of Columbia specifically outlaw 3D-printed guns, according to Everytown for Gun Safety, a gun control advocacy group.

“Technology has evolved and 3D printing has really become an emerging threat in a very new way,” said Monisha Henley, the senior vice president for governmental affairs at Everytown for Gun Safety.

The focus on 3D-printed guns comes as states continue to debate a range of firearm policies, including assault weapon bans, restrictions on high-capacity magazines and efforts to curb the spread of convertible firearms — weapons modified with devices such as switches, or auto sears, that can allow semiautomatic firearms to fire more rapidly.

A new, controversial Virginia law banning the sale, purchase and transfer of certain assault weapons is set to take effect July 1, though a handful of local sheriffs and prosecutors have vowed not to enforce it. Some critics have argued that the new law infringes on the Second Amendment rights of law-abiding citizens, and conflicts with legal precedent set by the U.S. Supreme Court.

Another new law in neighboring Maryland, set to take effect in October, will prohibit a person from manufacturing, selling, purchasing, receiving or transferring certain machine-gun-convertible pistols. A similar law was also adopted in Connecticut this year.

Legal challenges

Some opponents argue that outright bans on 3D-printed guns are unlikely to stop criminal activity and instead raise significant constitutional concerns.

“The gun is not the problem. The individual committing the crime is the problem,” said William Sack, the senior director of legal operations at the Second Amendment Foundation, a nonprofit gun advocacy and litigation group.

Sack added that stricter enforcement of existing laws targeting violent crime and prison time would be more effective deterrents.

Some gun rights advocates also argue that Americans have long been allowed under federal law to manufacture firearms for personal use, framing it as part of an American tradition. They also contend that states are increasingly targeting the dissemination of information rather than addressing criminal conduct directly.

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Privately made firearms, including those made through 3D-printing, have drawn concern from some prosecutors and law enforcement officials, who say the weapons can complicate criminal investigations. There is less consensus on broader proposals that regulate 3D printers or digital design files themselves, with debates often centering on enforceability and constitutional concerns.

Gun control advocates have countered that these policies are intended to get ahead of a rapidly evolving threat.

“We are trying to make sure that firearms don’t get in the hands of people who shouldn’t have one,” said Henley, of Everytown for Gun Safety.

Henley said the goal is preventive measures — focused on reducing harm and strengthening community safety — rather than waiting for a high-profile incident to drive legislative action.

“We can’t just focus on the symptoms, but we actually have to focus on the source,” Henley said.

Several new laws and legislative proposals have drawn criticism because they focus on digital design files used to create firearms. Opponents contend those files should be protected under the First Amendment because they constitute information that can be shared, stored and transmitted online.

A firearm blueprint can be emailed, stored on a flash drive, posted online or shared through encrypted platforms long before a weapon is ever produced.

In February, the 3rd U.S. Circuit Court of Appeals ruled in favor of the New Jersey attorney general’s crackdown on the online gun business Defense Distributed over its distribution of computer code for 3D-printed guns. The court ruled that the First Amendment does not protect purely functional forms of computer code as free speech.

Sack, of the Second Amendment Foundation, which took on the Defense Distributed case as legal counsel, told Stateline that the group is actively monitoring new legislative developments and strategically bringing cases to protect gun rights.

Untraceable firearms

Gun policy experts often point to the rising number of ghost gun recoveries over the past decade and say that cheaper, more accessible 3D-printing technology has made it easier to manufacture untraceable firearms at home.

From 2017 through 2023, approximately 92,700 suspected privately made firearms, or ghost guns, were recovered by law enforcement and traced, according to the federal Bureau of Alcohol, Tobacco, Firearms and Explosives. Those traces were linked to 1,692 homicide-related offenses and 4,106 other violent crime offenses.

This year alone, dozens of cases nationwide have involved the manufacturing and distribution of 3D-printed guns. In one case in New York, an alleged ghost gun dealer was tied to at least eight shootings in New Jersey, according to law enforcement officials.

In Maryland, police said two high school students who brought guns to school were found to have a 3D printer, along with multiple firearms, ammunition, magazines and other accessories, at their homes.

Digital blueprints can be shared online, downloaded instantly and modified by users, making enforcement more complicated than regulations aimed solely at physical weapons.

In response, researchers in recent years have explored ways to improve identification and tracing of 3D-printed firearms, including analyzing printing patterns, layer markings and other manufacturing characteristics that could link recovered weapons to specific printers or production methods.

A study published earlier this year in the peer-reviewed journal Forensic Chemistry, led by a team of researchers in Australia, found that certain 3D-printing materials known as filaments can carry distinct chemical signatures that may help forensic investigators connect seized firearms to their source materials.

Distinguishing between filaments could allow law enforcement to link cases together, identify and disrupt supply chains and potentially trace weapons back to manufacturers or distributors, according to the study.