Here's how the researchers' tracking system, dubbed the "PrinTracker," works: 3D printers discharge material, usually plastic, in layers until they form an object. According to researchers, each layer has tiny wrinkles, which are supposed to be uniform. But each printer, together with its nozzle size and the type of plastic used, causes miniscule imperfections. Researchers refer to that as its "fingerprint," which can be as tiny as a half millimeter.
The research team tested their system by printing five door keys each from 14 different commercially available 3D printers. After creating digital images of each key, they developed an algorithm to calculate variations of the imprints on the key down to the millimeter. They then added that information to a database.
According to the study, the researchers were able to match the key to its printer 99.8 percent of the time. They ran another round of tests 10 months later "to determine if additional use of the printers would affect PrinTracker's ability to match objects to their machine of origin," according to the study's release. The results were exactly the same.
"Like human beings, they [3D guns] have their own writing signature," Xu said. "Finding these signatures could help forensic experts and police."
But the team's method has its limitations. "Fingerprinting" 3D guns requires the same tool used for fingerprinting people: a database.