So an interesting video using a fiber laser to mark plastic parts (and before someone freaks running down the hall yelling “chlorine” it’s worth watching the video). The PETG bleaching was fascinating for making backlit indicator panels… I have 2 layer acrylic that does a similar thing, but the advantage of a 3D printed part is the ability to have a complex surface shape.
you were going to try some of this and post the results right? 
My fiber laser has gotten lost in the mail…
Just picture sally struthers with a sad expression: “did you know there are doctors in Boston who have to use tube based CO2 lasers? They don’t have a fiber laser and so they have to go to bed knowing they can only mark metal with ceramark spray. Please donate lasers to help them sleep better at night…”
Yours and mine must be languishing in the same warehouse somewhere I did have some 3D print starts that I stopped after the first couple of layers so they were just a sheet of white. I painted them with a black sharpie and at full speed about 30% power or so they engraved only slightly but completely removed the sharpie. That worked pretty well and I’m thinking I might try it with black spray paint or other inks to see if it is a technique I could actually use.
I’m not a doctor, and 
I don’t play one on TV either, but I think my fiber laser must have gotten lost in the mail, too.
This time he used it on another project and I have to say looked amazing:
