

It would be nice if you could post something where we can examine the source. (EDIT: the link has been changed since I wrote this)
I found this article: https://www.techspot.com/news/108720-hidden-fingerprints-inside-3d-printed-ghost-guns.html
There they say that it’s not yet ready to be used in evidence, but the problem with that is that most forensic “science” is generally misapplied and nowhere near as conclusive as the police want us to think. They can usually massage the results to tell a jury what they want to be true. That would be my concern with this kind of technique.
Also, if you’re going to the trouble of making a 3d printed ghost gun that will be used in a crime, you could always hide the toolmarks with a sander. You could also treat the surface with resin which would make the markings practically unrecoverable. I’ve started doing both of these for my prints and I love the results just for the aesthetics, so it’s not such a stretch to imagine a gunsmith doing the same.
Yup, Behind the Bastards did an excellent two parter on forensic science in general:
https://www.iheart.com/podcast/105-behind-the-bastards-29236323/episode/part-one-the-bastards-of-forensic-170035753/ https://www.iheart.com/podcast/105-behind-the-bastards-29236323/episode/part-two-the-bastards-of-forensic-170702749/
They make a good point that real science is involved, but by the time it makes it into the police’s hands it’s mutated into essentially a mechanism to manufacture convictions. Grifters get hold of the science, and cops are like the perfect marks, because they’re just primed for anything that will confirm their existing biases, plus they’ve got massive state budgets to play with, and they’ll happily give the grifters legitimacy.