PP or Pe will both slowly burn and will both drip. Pe will always smell of candle wax. Cut off a sliver and put a match to it to try this out. The test for these is simple. PVC doesn't burn, it just gets soft and stinks.
Acrylics burn slowly and smell sweet.
ABS burns quite well and gives off black fumes and it pongs. But super for ping pong balls which, although modified with Naptha, cannot be excelled by any other known plastic. Lastly, please preclean before painting. To get a better job of adhesion, sand down very slightly, too. I want to post a question or inquiry of my own.