I'm sure this is not my idea, but I don't remember where I may have first heard of it. I peel the backing off a sheet of Mylar and tape it to a table sticky side up. Then I peel the backing off each playfield plastic and stick it on the Mylar sheet. Trimming all the plastics is the tedious part. I don't Mylar any plastic that is significantly transparent. We've all seen plastics where the art was worn through from a screw head or a ball guide. The idea is that the Mylar would have to be worn through before the art could be damaged. I first tried this back in 2008 on a set of Space Station plastics. More than ten years later I see no ill effects.