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What California Is Alleging

• San Diego County alleges Polymaker deliberately marketed 3D-printer filament to people who manufacture unserialized firearms.
• The lawsuit does not claim ordinary 3D-printing filament is illegal — its theory focuses on how Polymaker allegedly marketed certain filament for firearm production.
• California seeks civil penalties, disgorgement and an injunction in a case testing how the state's firearm-precursor law applies to an otherwise lawful raw material.

By Samuel López | USA Herald

SAN DIEGO — California's fight against homemade ghost guns has moved upstream from finished weapons and unfinished receivers to something far more ordinary: rolls of plastic.

San Diego County Counsel, acting on behalf of the People of California and working with Giffords Law Center, filed a civil lawsuit against 3D-printing filament manufacturer Polymaker LLC on October 5 in San Diego County Superior Court. The complaint accuses Polymaker of deliberately marketing and selling filament to Californians for use in manufacturing illegal firearms.

The distinction at the center of the case matters. 3D-printer filament itself is not illegal.

The county instead relies on California's definition of a “firearm precursor part.” Under Penal Code §16531, the definition can encompass an article marketed or sold to become, or be used as, the frame or receiver of a functional firearm once completed, assembled or converted. The lawsuit alleges Polymaker's marketing brought certain filament within that definition. 3D Printing Journal

One person receives considerable attention in the complaint — Sean Aranda, known online as “The 3D Print General.”

Aranda produced 3D-printing content and wrote books on the subject. His YouTube channel, which included firearm-related material, was removed in 2023 for violating YouTube's firearms policies. Polymaker had sponsored Aranda and produced a special-edition spool associated with him before later hiring him. He has since held customer-experience and technical-account roles with the company. The 39-page complaint references Aranda dozens of times and cites Polymaker's relationships with firearm-focused creators and affiliates as evidence supporting the county's marketing allegations. Tom's Hardware

Affiliate marketing itself is commonplace online. The county's allegations concern how those relationships allegedly intersected with communities producing 3D-printed firearms — not affiliate marketing generally.

The complaint also cites a San Diego police investigation this spring. According to the lawsuit, officers recovered Polymaker filament from the home workshop of a 16-year-old suspected of planning a school shooting, along with printed firearms and firearm components police believed he intended to sell.

That allegation does not establish that Polymaker knew about, participated in or caused the teenager's alleged conduct.

The case is part of a broader California effort targeting components associated with ghost-gun production. Earlier this year, California Attorney General Rob Bonta and San Francisco sued operators associated with Gatalog, an online repository containing digital files that can be used to manufacture 3D-printed firearms. Los Angeles Times

Polymaker presents a different target. It sells physical material consumed by 3D printers — a product with many lawful applications.

That makes the statutory language central. The county is not merely alleging Polymaker filament can become a firearm component. Its complaint alleges the company's own marketing brought certain products within California's firearm-precursor law.

San Diego County seeks injunctive relief, civil penalties and disgorgement. The litigation now puts before a California court whether the marketing of an otherwise lawful raw material can bring that material within the state's firearm-precursor framework.

About the Author

Samuel López is a USA Herald reporter and news correspondent who has reported for the publication since 2022. He has more than two decades of legal-sector experience analyzing state and federal litigation and complex legal matters, experience he brings to coverage of developing lawsuits, statutory interpretation and technology.

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