A hot potato: California's long-running battle against 3D-printed guns has just seen San Diego County, acting on behalf of the state, sue Polymaker LLC, one of the world's largest 3D-printing filament manufacturers. The lawsuit claims that Polymaker intentionally markets and sells its filament to Californians with the express purpose of creating illegal ghost guns.

The complaint, which was filed on October 5 in San Diego County Superior Court, acknowledges that 3D printing filament is not illegal. However, it alleges that Polymaker intentionally marketed its product toward ghost gun aficionados so they could turn its filament into a regulated "firearm precursor part."

California law describes a firearm precursor part as including an article marketed or sold to the public to become or be used as the frame or receiver of a functional firearm once completed, assembled or converted.

The complaint adds that Polymaker monetized the ghost gun community by supporting and hiring Sean Aranda, also known as The 3D Print General. After he was banned from YouTube in 2023 over firearm policy violations, Polymaker offered him a job as Head of Customer Experience. He is now a Senior Technical Account Manager at the company.

The suit alleges that hiring Aranda was part of Polymaker's effort to target 3D-printed gun enthusiasts.

The complaint also points to affiliate payments and firearm-themed products as evidence that the company actively cultivated this particular market for its filament.

The county is seeking civil penalties, the return of revenue from the alleged unlawful practices, and an injunction. It empahsizes that the lawsuit doesn't seek to ban filament sales in California.

It was reported in May that California lawmakers had advanced AB 2047, requiring printers to block firearm designs, checking them before printing begins. Governor Gavin Newsom signed an amended version in September, although its requirements depend on an industry standard being published. That latest effort targets the machines rather than how their raw materials are marketed.

In August, a Texas federal judge declared parts of the ATF's ghost-gun rule unconstitutional and blocked their enforcement against Defense Distributed and Second Amendment Foundation members. The federal ruling doesn't settle the case against Polymaker, which concerns California law.