Is Polymaker Liable for Ghost Guns? California Files First-of-Its-Kind Lawsuit
In one of the first tests of California's 2026 firearm law, San Diego County alleges Polymaker crossed the line into unlawful business practices by directly marketing its filament to DIY gun builders.
Polymaker, the popular maker of 3D printing filament, is facing a civil lawsuit brought by the San Diego County in California that accuses it of deliberately promoting its products for the purpose of making ghost guns.
Filed last week, the lawsuit, People v. Polymaker, alleges that the company knowingly promoted certain filaments for firearm manufacturing applications despite California restrictions on the unlicensed production of unserialized firearms. California is accusing Polymaker of unlawful business practices, not prosecuting the company for a criminal offense.
The county alleges that Polymaker developed firearm-themed products, collaborated with influencers producing 3D printed gun content, paid affiliates to promote its filament to those audiences, and provided technical guidance for firearm-related applications. The county also alleges that Polymaker directly participated in online communities focused on 3D printed firearms.
In a statement, the country said: “We allege Polymaker did more than sell a product that some customers happened to misuse. The company created firearm-themed products, partnered with gun-printing influencers, paid affiliates to promote its filament to gun-printing audiences, provided technical guidance for firearm applications and engaged directly with online communities devoted to printing guns.”
A new California law, introduced in January 2026, specifically prohibits businesses from knowingly or recklessly helping others manufacture firearms unlawfully. San Diego County alleges that Polymaker crossed that line by actively promoting its filament for firearm production. However, the alleged activities are not inherently illegal, and the county must establish that Polymaker’s conduct violated California new law.
One relationship highlighted by county officials involves Sean Aranda, a 3D printing content creator associated with firearm-related projects. According to the county, Polymaker sponsored Aranda and subsequently hired him in 2023 as its Head of Customer Experience. Currently Aranda is Polymaker’s Senior Technical Account Manager.
Sean Aranda, known online as “The 3D Print General,” is a prominent figure in the DIY 3D printed firearms community. He hosted the 3D Printed Guns with Sean Aranda podcast, interviewing firearm designers and developers, and produced videos exploring 3D printed weapons before YouTube banned his channel in 2023 for policy violations.
The county argues that these activities represent deliberate efforts to cultivate a market for materials used to manufacture unlawful, untraceable firearms, rather than incidental sales to customers who might use filament for that purpose.
The county is asking the court to order Polymaker to stop the alleged practices, pay financial penalties, and hand over any profits made through unlawful activities.
The case is among the first three lawsuits brought by San Diego County’s newly established Consumer Fairness and Public Protection Unit, operating within the Office of County Counsel.
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