➀ Forensic expert Kirk Garrison identifies unique toolmarks on 3D-printed ghost guns, linking them to specific printers through microscopic patterns in filament layers;
➁ The method can narrow investigations but faces limitations from variable factors like nozzle settings and print bed positioning;
➂ This pioneering forensic approach, though unproven in court, highlights growing efforts to combat untraceable weapons amid challenges in 3D printing regulation.