3DPrinting

The reality is that the markings left on bullets aren't as unique as NCIS would have you believe. A lot of them DO change over time (or even just field stripping a gun).

But the key is that in those first N hours/days, it can be some very substantial evidence. 9 mm round was left embedded in the politician and the chief suspect has ten 9 mm PCCs? Let's test all ten of those and see if we get a match. And so forth.

In that case: Assuming this holds true (I read the article a few days ago and it is currently very hazy), the same could be done with 3d printers. Ghost gun used in a case and the suspect has a 3d printer? Well... checking the print logs is probably still easier. But one could imagine a world where there is a court order to print a special benchy to compare tooling marks.

And... much like with guns, someone who is educated can take precautions.

Exactly!

The belief that forensics is reliable is unfounded. I don’t know the stat but last I remember reading it, it’s pretty low that they can prove anyone did anything. More murderers haven’t been caught than have.

This kind of thing already happens in established fields of forensics all time and if they couch everything in enough authoritative sounding language nobody who doesn’t already know a whole bunch about the topic is going to be able to call them out on it.

Bingo, the goal is not to actually trace 3d printed guns, it's to add another piece of evidence they can slap onto the target of their investigation to improve the chance of getting a conviction. Whether the accused is actually guilty of anything is truly irrelevant to the intended purpose of these kind of things, they are in practice assumed guilty by the prosecution unless proven innocent. The point is simply to make a convincing case to a judge or jury.

There's also all the mess of slicer and printer settings. It would be interesting to give someone a collection of parts with different nozzle sizes, extrusion widths, pressure advance settings, temp settings, print speeds/accelerations, etc

Just change nozzles every print, you can get cheap Chinese nozles for less than a $1 a pop.

I think there was a study that showed every 3d printer leaves a sort of fingerprint, and they can identify which printer printed what object.

You don't have to buy it for them to convince 12 average citizens that they used wizardry and science to definitively prove it's 'real.' See bite mark analysis, fiber analysis, hair analysis, etc, etc, etc. Court rooms are full of pseudoscience because it helps convict more people.

Hell, you're not even gonna get that far. I don't think there's a forensic lab within 2000 miles of me that could do this kind of work. All that funding goes to guns and cover ups.

You could probably map resonance artifacts, but you have to isolate layers that were printed at the same speed and direction. However, the second you tighten a belt or screw, that pattern will change and I am not sure how consistent resonance patterns would be on a bed slinger. (The quantity and density of printed plastic may change the resonant characteristics of the entire printer. This may be less of an issue on a core xy.)

Thinking waaay outside the box.. In some cases, I have seen extruder gear marks on the filament create artifacts on a print. Every gear pattern should be unique, but measurable differences would probably be micron or sub-micron.

Maybe you could map the surface of textured beds as I seriously doubt that those patterns would be consistent and more prone to randomness from the factory.

There are a ton of conditions that could generate unique artifacts on a print, now that I think of it. Hell, even a printers PID tuning can leave visible and repeatable errors.

I half expect Bambu labs to already do and be furiously trying to come up with a scheme to monetize it.