I have used the SEM 3 step process with good sucess. I start by washing well with soap and water... with a soft brush if needed to get in corners. Then use 1) the SEM cleaner 2) the SEM adhesion promoting primer. This softens the surface of the plastic so the dye sticks 3) dye. A light coat right after the adhesion promoter then one or two more after the first coat flashes off. Never a peel, flake or problem.

Eastwood sells the kits.