I made the mistake of getting exterior acrylic paint on the plexiglass windows of my garage thinking that I would be able to scrap it off the same way you would with a glass piece. My knife/scraper scratches the plexiglass. Any suggestions to remove the paint? It was applied about 6 months ago.
A water-based stripper should do the trick. It works by penetrating the paint and reacting somehow to expand its volume once it has soaked through the paint, breaking the bond between the paint and the plexiglass (unlike solvents). Since it's not a solvent it won't harm acrylic such as Plexiglass. If it's an oil based paint I'm not sure what you can use, but it's ok for latex based. Check out Motsenbocker's Lift Off #5 at http://www.liftoffinc.com/product_5.htm