Hi Gang,

Another good paint for plastic is the stuff sold for bumpers, usually
some sort of "vinyl" paint.

I've used it for plastic, rubber, fiberglass targa tops, air dams, etc.
with very good adhesion, flexibility and durability.  I used Duplicolor
brand with good results. Comes in black and a few other boring colors.

The most important aspect to painting plastic is prep, you have to
clean and sometimes sand the surface.  For a last prep step a wipe-down
with acetone or other solvent is great.  Needles to say it's best to
remove the bumper tip and prep and paint indoors, and not to rush
things.