If you use a quality paint and clean the plastic well beforehand, the paint I mentioned above works exceptionally well. You don't NEED a dye to absorb if you lay down a quality coat of paint, and do the prep work right.

Also, keep in mind that the vinyl "dye", which is really just a paint with really aggressive solvents that melt the plastic allowing the paint to adhere better, is actually more dangerous to the plastic. accidentally lay it on too thick and your rugged model m case turns to saggy soft plastic... granted it will strengthen back up once the solvents flash off, but it's a more dangerous method for doing the same thing, put a coat of paint on a plastic case (accidentally touch or bump the board while flashing and the plastic is marred, drop something on it and it will likely fracture)
I like plasti-dip because it's EASY to reverse... once it is fully cured, it can be peeled off like sunburned skin! mm!