Hi Don.
I do plastic for a livng.
Use a 60 grit disc sander to get the
molding to size. After that you can
either scrape or sandthe edges to
a nick free polished state. It doesn't
take but a few minutes to trim plastic this way.
ALSO you can use a SHARPIE brand felt
pen to mark the plastic. All the ink comes
off with alcohol. DON"T use a magic marker
because it won't come off. Red china markers work
well also.

Scott.