I am not sure most 3D Print people realize that SOME plastics can be engraved with a LASER.
It mostly dependent on the color. My goal is to burn out the color without melting the plastic.
I have two style of LASER available. My high power (20 watt) UV LASER and a low power (2 watt) IR LASER. The best results for me have been with the IR LASER. I Have a lot more room to explore with both LASER types. I do get good results with certain colors.
Red Plastic is Not good with an IR (infra-red) LASER. But grays and browns work well
The example in the lead photo in PLA in Lt. Gray. The Mail address on the back is LASER engraved.
HERE is a link to an earlier article I wrote in another one of my 3D printing BLOGS, Dimensional Print.