Ghost gun legislation casts shadow over 3D printing

Proposed bills in New York and elsewhere threaten makers, Adafruit says

State and federal lawmakers have stepped up their efforts to prevent the creation of 3D printed guns. But Adafruit, a maker of electronics kits, warns that the proposed legislation is so broad it threatens everyone involved in open source manufacturing and technology education.

Recent bills attempting to grapple with this issue include New York's FY 2026–2027 executive budget bill (S.9005 / A.10005), Washington State House Bills 2320 and 2321, and the 3D Printed Gun Safety Act introduced last June in the US House and Senate.

The renewed enthusiasm for clamping down on 3D printing technology follows allegations that Luigi Mangione killed UnitedHealthcare CEO Brian Thompson in December 2024, with authorities saying a 3D-printed "ghost gun" recovered after his arrest was consistent with the weapon used.

Adafruit, which previously raised concerns about the Washington State proposals, said on Tuesday that the New York bill is also problematic.

"Buried in Part C is a provision requiring all 3D printers sold or delivered in New York to include 'blocking technology,'" the company said in a blog post. "This is defined as software or firmware that scans every print file through a 'firearms blueprint detection algorithm' and refuses to print anything it flags as a potential firearm or firearm component."

This requirement would cover a broad set of manufacturing machinery, Adafruit claims, not just resin-based stereolithography (SLA) and fused deposition modeling (FDM) additive printers, but also Computer Numerical Control (CNC) mills and "any machine capable of making three-dimensional modifications to an object from a digital design file using subtractive manufacturing."

Last month, New York Governor Kathy Hochul announced the legislative proposals to combat 3D printed and illegal firearms. "From the iron pipeline to the plastic pipeline, these proposals will keep illegal ghost guns off of New York streets, and enhance measures to track and block the production of dangerous and illegal firearms in our state," she said in a statement.

The New York bill would, among other things, criminalize the intentional sale, distribution, or possession of digital instructions to illegally manufacture a firearm or component parts without a license; require 3D printer makers to implement technology to block their machines from creating firearms and component parts; and require the sale or transfer of any 3D printer to be done in-person.

Several states already have laws that disallow the distribution of digital gun files, according to gun safety group Everytown: "Delaware and New Jersey make it illegal to distribute any files within the state that can be used to program a 3D printer to make a firearm, while California creates a civil cause of action against these actors."

Manhattan District Attorney Alvin L. Bragg, Jr. maintains more needs to be done to limit the availability of 3D printed firearms, echoing concerns voiced by federal lawmakers.

Adafruit says the obvious flaw in the New York bill is that "you cannot reliably detect firearms from geometry alone."

"A firearms blueprint detection algorithm would need to identify every possible firearm component from raw STL/GCODE files, while not flagging pipes, tubes, blocks, brackets, gears, or any of the millions of legitimate shapes that happen to share geometric properties with gun parts," the company said. "This is a classification problem with enormous false positive and false negative rates."

The company argues, among other recommended changes, that lawmakers should focus on punishing intent and unlawful behavior rather than the possession of machinery and should drop mandatory file-scanning because it won't work with open source, offline, or custom workflows.

Surveillance should not be built into our tools, the company contends. Instead, prosecute illegal acts. ®