Did they silkscreen on them? What was the method? How did they print on them? If anyone has experience or knowledge please let me know. Thanks
I don't know but I'd guess screen printing. But when I was a young entrepreneur I used to screen print a lot of shirts but I was very low budget and did water-based inks. I printed on some hard surfaces like hockey pucks with good results but the ink didn't stick well. We have shops around here that do control panels and they screen print them but they might be using a solvent based ink and a flash dryer.
I would have guessed Tampo Pad Printing which is also used for doing parts of toys like Barbie's face. https://en.m.wikipedia.org/wiki/Pad_printing When this guy finally shows us the result I'm surprised how good it is The printing I have always wondered about is reversed printng. I have at least one Sony Radio where the case is painted silver except for the SONY logo which is actually the dark plastic the case was made from underneath the paint, exactly the same as you see if the radio gets scratched.