Quoted from wayout440:I would say avoid Novus on plastics with art, the Novus is like very fine liquid sandpaper. I use technical grade alcohol (99.9% anhydrous alcohol). Tech grade alcohol also cleans rubber parts up very nicely.
Don't use alcohol on older plastics unless you know it's safe. Alcohol softens the plastic on Williams EMs enough that you can leave a finger print in it. I don't know when things changed or which other manuf. used that type of plastic.
Novus 1 isn't abrasive and seems to be fine for the art side of plastics, but as someone said above mild dish soap should also work.