On June 26, 2026, the Civil Police of Rio de Janeiro, through its specialized firearms, ammunition, and explosives unit, raided a clandestine workshop in Rio das Pedras, on the city’s west side. Investigators said the group used a 3D printer seized at the scene to produce pistol frames and structural rifle parts in polymer and then completed them with metal parts. Early reports described those parts as imported, but police said on the day of the raid that they were still determining the metal’s origin. Police described the operation’s main target as an international arms and ammunition trafficker who supplied criminal groups.
Recent Brazilian cases show final assembly moving closer to criminal users, while documented workshops still rely on outside suppliers for ammunition and functional metal parts, and the designs that make the weapons possible circulate outside the workshops. After the United States designated the Primeiro Comando da Capital and the Comando Vermelho as terrorist organizations, those remaining supply relationships became the clearest source of investigative leads and legal exposure.
Brazilian coverage treated the raid as another story about criminals printing their own guns. In this case, the strongest investigative trail runs through the supply chain, above all through the acquisition of ammunition. Investigators say the group used falsified credentials to buy from a specialized dealer in Santa Catarina and directly from an ammunition manufacturer, acquiring more than 10,000 rounds of 5.56-millimeter and nine-millimeter ammunition within a few months. None of that supply crossed an international border, and the printer could not replace the inputs the weapons needed to function.
I spent 23 years with the São Paulo Civil Police, in its specialized organized crime and narcotics units, and seizures like these register, to an investigator, first as logistics and only then as technology. The question that drives an investigation is who supplied what. In 2026, that question gained new legal weight. Following the designations, knowingly providing weapons, components, or technical assistance to either organization can trigger federal criminal liability for material support where U.S. jurisdiction applies, regardless of whether a supplier printed, assembled, or conventionally manufactured the weapon. The new element is what those familiar trails can mean under 18 U.S.C. § 2339B. An ammunition purchase, payment, finished component, or delivered design file can become the basis of a material support charge when the facts establish the required knowledge and U.S. jurisdiction.
An Emerging Domestic Production Channel
Brazil has a growing record of documented 3D-printed firearm cases. On March 12, 2026, an integrated operation led by the Civil Police of Rio de Janeiro State and the state prosecutor’s cybercrime unit, with support from the Ministry of Justice and Public Security, dismantled a structured network that developed, produced, and sold 3D-printed firearms and accessories.
Code-named Shadowgun, the operation involved 36 search warrants and five arrest warrants targeting 30 suspects across 12 states, with support from Brazil’s intelligence agency. Officials said the investigation originated in information exchanged between U.S. Homeland Security Investigations and Brazil’s federal cyber operations laboratory. The network circulated digital weapon designs and assembly manuals through online platforms.
Other Brazilian cases show the same technology entering clandestine workshops and conventional criminal logistics. Authorities dismantled a network that printed weapon components and stored finished nine-millimeter barrels. In another case, authorities intercepted printed weapons transported alongside a drug shipment. Regional analysts describe Latin American firearms markets as hybrid systems in which legal, diverted, and improvised weapons overlap, and they document a growing presence of 3D-printed firearms. Barriers to entry appear to be failing as technical knowledge circulates through encrypted platforms, online repositories, and extremist networks, beyond the reach of physical border inspection.
Empirical studies mainly associate 3D-printed firearms with criminal activity, lone actors, online firearm-building communities, and small workshops, as sustained organizational supply chains remain uncommon. One dataset of 225 documented incidents from 2013 through July 2024 linked 145 of these incidents to criminal activity and 35 to terrorism. Most involved individuals acting alone, not organized groups. Limited access to conventional firearms helps explain the appeal of printed weapons in some terrorism-related cases.
Brazil broadly follows this pattern. Direct evidence linking 3D-printed firearms to either the Primeiro Comando da Capital or the Comando Vermelho remains limited. Open-source reporting has associated some online images and claims with the Primeiro Comando da Capital, but these represent isolated experiments or peripheral acquisitions, not an established supply channel. Separately, Rio de Janeiro prosecutors reported a previous-year case in São Gonçalo in which authorities seized a printed weapon from a person linked to the Comando Vermelho. A single seizure does not establish 3D printing as a regular factional supply channel.
Brazil’s largest criminal networks still depend heavily on the diversion and trafficking of conventional firearms, ammunition, and components. Available seizure data from Brazil’s Southeast region identify Brazil, the United States, Germany, and Belgium as the leading countries of manufacture among military-style firearms with identified brands. Criminal groups use these military-style firearms to control territory, sustain armed-protection markets, and confront police. Printed and hybrid firearms remain a small share of this market. Their importance lies in what they reveal about how established supply chains have been adapting.
What the Workshops Print, and What They Still Need
Durable 3D-printed firearms are hybrid weapons. Leading designs combine a printed polymer body with metal pressure-bearing parts, principally the barrel and the bolt or breech component, along with springs. Consumer-grade plastic cannot replace those parts, as weapons printed entirely or mostly in polymer are less reliable and less durable. A weapon meant for repeated use needs metal above all in the chamber area, where firing pressure peaks.
Those metal parts need not begin as regulated firearm components. Developers engineered designs such as the FGC-9 to require no commercially produced firearm components: The barrel can be made from commercially available steel tubing and the bolt from ordinary metal bar stock, materials sold by industrial suppliers for many legitimate uses. In a country with a large steel industry and wide access to machining equipment, none of those materials has to cross a border.
Operation Shadowgun exposed the design and distribution side of the same market. Prosecutors charged an engineer with developing the Urutau, a polymer carbine built between 2021 and 2024 and released through online repositories. Investigators estimated the build cost at 600 to 800 reais (about $115 to $155). The design spread beyond Brazil, with New Zealand police seizing one in April 2025. Builders can make the Urutau almost entirely from polymer using domestic printers and basic metalworking. It still requires functional parts and accessories, however, which investigators say the developer also sold. Here, too, the record shows local production paired with a separate supply of functional parts, without establishing their origin.
The Brazilian cases examined here involve two kinds of inputs, each leaving a different investigative trail. When a finished barrel or bolt reaches a workshop through a commercial or illicit firearms channel, the transaction reveals more about the buyer’s intent than the purchase of steel tubing, metal bar, or general-purpose tools. Those materials have many lawful uses, so their purchase records reveal far less.
Seizures cannot directly explain why documented workshops obtained functional parts separately, when local fabrication was possible. They show the outcome, not the reasons. Comparative evidence indicates that 3D printing becomes more relevant where conventional firearms are difficult to obtain. Brazil presents the opposite condition: Trafficking and diversion keep finished weapons and components accessible. Confirming that explanation would require evidence not yet available in the public record, including cost, production time, failure rates, and the technical capabilities of these workshops.
Ammunition remains a dependency that the documented workshops have not replaced. None of these cases involved producing functional cartridges. Brazil has domestic manufacturers and a large licensed retail network, which the credential fraud in Rio das Pedras exploited. In the cases examined here, 3D printing changes weapon assembly but leaves the ammunition supply intact.
Where the Supply Chain Is Heading
Roberto Uchôa’s analysis of Rio de Janeiro’s rifle economy traces that trajectory. In “The Gunpowder Hegemony,” he argues that the rise of ghost guns, computer-controlled machining, and 3D-printed receivers reflects growing domestic production capacity within Rio’s criminal ecosystem. Groups assemble, modify, and partially manufacture weapons closer to the point of use, rather than receiving complete imported rifles. He describes the same division: receivers milled or printed locally, while springs, triggers, and pins arrive separately. The seizure record examined here supports that assessment: Assembly, modification, and frame production have moved into local workshops. Design capability has advanced further still: Prosecutors say the developer designed the Urutau in Brazil, and New Zealand police later seized a weapon based on that design.
Neither Uchôa’s analysis nor the open sources examined for this article document workshops producing pressure-bearing components from commercial stock. An early sign of that shift would be forensic evidence in a Brazilian case of a barrel rifled from commercial tubing or a bolt machined from metal bar stock. A verified recovery would show that outside sourcing is no longer necessary for those components in at least some Brazilian workshops. If such recoveries became a pattern, the investigative window would be closing.
Operation Florida Heat is the clearest documented example of cross-border component sourcing at scale. In 2022, the operation dismantled a network that bought firearm components in the United States, shipped them to Brazil, and assembled the weapons in Vila Isabel using computer-controlled milling. Brazil’s Federal Police (Polícia Federal) and Federal Public Prosecutor’s Office (Ministério Público Federal) ran the case with U.S. Homeland Security Investigations, moving against 10 million reais (approximately $1.93 million) in assets. This case establishes what the recent seizures leave open: components acquired abroad and assembled inside Brazil. It documents one model, not a universal pattern, and brings U.S.-linked persons, territory, and payments into the chain.
Material Support and the Printed Gun
On May 28, 2026, the United States designated the Primeiro Comando da Capital and the Comando Vermelho as Specially Designated Global Terrorists. On June 5, 2026, Washington designated both organizations as Foreign Terrorist Organizations. Under 18 U.S.C. § 2339B, anyone who knowingly provides material support or resources, including weapons and other tangible property, to a designated organization can face criminal liability where U.S. jurisdiction applies. The Supreme Court has held that the statute requires knowledge of the group’s designation or of its terrorist activity, not a specific intent to further that activity.
If a supplier knowingly provides a rifle to a designated organization, the same legal problem arises whether the supplier diverted the rifle, assembled it from trafficked parts, or completed it around a printed frame. For a supplier subject to U.S. jurisdiction and acting with the knowledge § 2339B requires, the statute does not turn on whether the supplier imported the item into Brazil or obtained it there. Printing adds one stage to a supply chain the statute can reach, a point I developed in earlier work on the designations.
Potentially exposed actors extend beyond traffickers moving complete firearms across borders. They may include an intermediary importing components, a seller of hybrid weapons, a workshop operator finishing firearms for factional buyers, or a facilitator moving parts or payments. These actors sit differently under § 2339B. Subsection (d) reaches U.S. nationals and permanent residents abroad. Buying or shipping components from Florida may place conduct on American soil, and routing payment through a U.S. financial institution may create another nexus. The designation identifies the organization — jurisdiction determines whether the statute reaches the supplier. An operator working entirely inside Brazil, with nothing in the chain touching the United States, falls outside § 2339B’s reach unless § 2339B(d) supplies a basis: an offense affecting foreign commerce, the offender later found in the United States, or conspiracy with someone already within reach. As sourcing and production move further inside Brazil, the portion of the problem the statute can reach shrinks with them. Its clearest application is the cross-border segment of the chain.
Digital design files raise a separate § 2339B question. In Holder v. Humanitarian Law Project (2010), the Supreme Court held that independent advocacy falls outside § 2339B, while activity coordinated with or directed by a designated organization does not. That distinction does not protect tangible support delivered to the organization. The Supreme Court reasoned that even support intended for lawful ends can free other resources for violence. A design published openly for anyone to download differs from a file delivered directly to a designated organization. The decisive facts are what the supplier knew and who received the support.
The statute’s reach is narrower than the global dataset might suggest. Printing by itself does not create material support exposure. The question arises only when a person knowingly uses 3D printing to arm a designated organization. A hobbyist printing a frame, an extremist downloading a design, or a criminal buyer with no factional connection does not automatically fall within the statute. Prosecutors still have to establish that the supplier knowingly provided support to the designated organization.
A Local Link in a Transnational Chain
The Rio das Pedras workshop shows the arms trade adapting through local assembly, while also revealing the limits of that change. The group printed the polymer frame on site, investigators said, but the components that made the weapon work, along with the ammunition that fed it, came from outside the printer. Investigators traced the ammunition to a specialized dealer and a manufacturer and said the group had deceived both with falsified credentials.
In the cases examined here, the supply side gives investigators more to work with than the printer does. The ammunition passed through licensed sellers whose records exist, and the fraudulent credentials left a paper trail. A purchase of general-purpose steel or common tools reveals little about what the buyer intends to build. The record has a survivorship problem: Authorities detected these workshops, several through those same traces. Detection does not change the incentive: Buying a finished barrel avoids the time, skill, and failure risk of making one. The record cannot show how often undetected workshops make that choice. The cases support a narrower claim about investigative leverage. When a workshop depends on outside suppliers, those transactions create traces investigators can follow. The forensic recovery of a locally machined barrel or bolt would be an early sign that the advantage is narrowing. For now, the documented Brazilian cases expose suppliers operating before the final assembly stage.
This lesson extends beyond Brazil. Printing can move final assembly closer to the user without eliminating the rest of the supply chain. Where that happens, suppliers, payments, and critical components remain investigative pressure points and, where jurisdiction exists, sources of legal exposure.
The U.S. designations of the Primeiro Comando da Capital and the Comando Vermelho as Specially Designated Global Terrorists and Foreign Terrorist Organizations do not bind Brazil or reclassify the factions under Brazilian law. Brazil rejected the U.S. terrorist classification and has not designated either group as a terrorist organization domestically. Cooperation remains possible on grounds both countries already recognize, though the designations do not by themselves allocate investigative resources or create new intelligence channels. The same evidence may support a U.S. material support case even though Brazil does not classify the groups as terrorists. Bilateral work must separate shared facts from divergent legal labels.
U.S. federal prosecutors and Homeland Security Investigations, working with Brazilian police and prosecutors, should prioritize the trails that 3D printing has not replaced: ammunition purchases, finished barrels and bolts, technical assistance, and payments. They should also distinguish a design published openly from one delivered to, modified for, or explained to a designated organization. The designations add a second evidentiary track: For each component, file, or payment, investigators must document the recipient’s identity, the supplier’s knowledge of the designation or terrorist activity, and the facts establishing U.S. jurisdiction. The Foreign Terrorist Organization listing creates a § 2339B charging option and requires U.S. financial institutions to retain and report funds in which the organization or its agent has an interest. The Specially Designated Global Terrorist designation blocks property and interests in property under U.S. jurisdiction. Extradition changes little. The designation does not expand the treaty’s list of extraditable offenses or override Brazil’s constitutional bar on extraditing native-born Brazilians.
None of that changes what happens on the ground: The supply model documented by the 2022 operation reappeared in August 2026, when police in São Paulo arrested a man accused of importing restricted firearm parts from Florida, assembling clandestine weapons, and supplying criminal groups in Rio de Janeiro. The printer moves final assembly into Brazilian territory, but not the supply. In that model, the trafficker who once moved complete weapons can move critical components, while a local workshop prints the frame in Brazil. What used to cross the border as a complete rifle can now cross it as a barrel, a bolt, or other functional parts. The chain has not disappeared: Investigators find it where those parts change hands.
Carlos Eduardo da Silva is a researcher and strategic intelligence analyst focused on transnational organized crime. He spent 23 years as an investigator with the São Paulo Civil Police, in its organized-crime (DEIC) and narcotics (DENARC) divisions, where his work centered on the Primeiro Comando da Capital (PCC). He holds a degree in public security and a postgraduate specialization in criminology. His current research examines the PCC as a system of criminal governance and its transnational expansion.
Image: Adisen Smith via DVIDS
