Also the ones who think this is something with even tiny chance of being viable in court anytime soon or will persist as an effective crimebuster for any notable amount of time if they do.

The above comments have already covered many possible variations complicating things, due to the settings and positions of how the machine was used to 3d print something. The article claims 3d printing tech has nozzles that have unique signatures. They would (or at least should) need to make sure it is actually unique by cross checking with other nozzles too. Lots of them really, just to make sure.

That might require finding multiple nozzles made in the same batch as the murder weapon, preferably unused, so they could attempt to recreate the crime version, to rule it out. It might be a nozzle manufacturer causing these imperfections where each batch of 10,000 nozzles is made in an extrusion plant or injection mold or done like solder ball grid array or pipefitters and play-doh (i honestly have no idea how they are made lol) and it turns out every nozzle in the first row has the same 'fingerprint' that warps the same way with use.

As technology progresses, parts should (but these days, idk) be made with more durable materials, with greater precision, capable of smaller scales or higher complexity and these unique signatures disappear for any easily detectable method. That's just the nozzles. In theory, that can apply to many if not all the parts.

I mean, Fabs for CPU are currently producing chips at what, 3 nanometers now? I just learned about electron-beam lithography too. The 3d printed smoking gun fingerprinting will be an anacronism before it's a specialization, in my opinion.