Each individual level of the print is called the print line

It's called a layer.

“So on the firearm, I’m seeing from the trigger guard—maybe print line 200—and the top of the magazine well—print line 400—the marks are staying consistent,” Garrison said.

...I don't even understand what that's supposed to mean? "The marks are staying consistent"? What marks? Consistent with what?

Even if they were able to match a print to a nozzle (which they won't be because it's a wear item that's constantly changing), nozzles are cheap and replaced often. You replace them in 2 minutes.

However, none of this will stop DAs from trying to use this shit as evidence, just like all the other junk science they pay people to lie about.

Also worth pointing out:

There are other issues too. All of Law and Blair’s tests were done with one kind of 3D printer—a Prusa MK4S. There’s hundreds of different devices on the market that all behave differently. Law also pointed out that brass nozzles warp over time themselves and may produce different results after hundreds of prints and that different nozzles made from different materials may work very differently. Law would also want an examiner rate study—a formal scientific inquiry into false positives and examiner bias.