Although 3D printing offers makers an incredible way to fully unleash their creativity, there’s a growing number of cases where it’s being used for criminal purposes. 3D-printed firearms remain a controversial topic, especially as their use continues to rise, as confirmed by a 2024 report from the United States National Library of Medicine (NLM). The NLM notes that 3D-printed weapons are “gaining popularity in various regions, regardless of the strictness of firearm regulations or cultural context, and not just as a last resort.” Since 3D-printed guns are unregistered and therefore untraceable, they present a major challenge for law enforcement investigations. That’s exactly where criminologist Kirk Garrison steps in. He has developed a forensic method to trace 3D-printed firearms back to their source.
Garrison, who works for the San Bernardino Sheriff’s Department, has long focused on the rise of 3D-printed firearms and firearm components. A few years ago, 3D printing was mainly used to convert semi-automatic weapons into fully automatic ones, but now Garrison increasingly encounters guns that are entirely 3D-printed. Through microscopic analysis, he noticed that the hardware used in the printing process leaves distinct markings on the printed objects. This “fingerprint” could potentially be used to determine the origin of the weapon. Garrison pursued this insight and co-authored an initial paper on the method in 2023 with Steven Pavlovich of the University of Western Australia. A second edition of the study, in collaboration with researchers from the University of Central Oklahoma, is now underway.
“Fingerprints” left by the 3D printer can be traced back to the specific model used.
Garrison’s method is based on his discovery of characteristic tool marks in the plastic of 3D-printed parts. In his research, he found that the filament follows specific paths during the printing process, paths that can indicate the exact model of printer used. Additionally, the texture of the printer’s metal heat bed leaves identifiable traces on the finished object. These clues make it possible to determine the type of printer involved. A custom algorithm developed for the project can even identify the specific print nozzle, allowing the printed weapon parts to be matched to the printer in 75 percent of cases, a promising development for forensic science.
However, it is important to note that so far, the analysis has only been conducted on models of the Prusa MK4S type. These printers, however, can be modified at will. With altered hardware or different 3D printer models, the results of Garrison’s forensic analysis are likely to vary significantly. As a result, the data is not entirely reliable.
Credit: Kirk Garrison
In addition, tracing a weapon back to the specific 3D printer model used contributes only marginally to an investigation. It’s also important to note that forensic methods can only be applied when there is already a reasonable suspicion of a crime. In this context, while Garrison’s approach appears promising, it is not yet ready for practical use. You can find more information HERE.
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Photo Cover: Liberator, ‘The first 3D-printed pistol shown in its individual parts.’