Researchers discover that every 3D printer leaves a unique "fingerprint" on prints, and they can be tracked back pretty accurately
They're looking at a square millimeter of print, which means they're reading the edge profile of the nozzle, in a small sample set. Similar to barrel markings on bullets.
On other words, not very accurate.
Despite decades of seeing this stuff on TV, bullet casing "fingerprinting" isn't
Yeah, it never proves that was the barrel a bullet came out of, just that it came out of a barrel just like that one.