I want to spray some slightly flexible plastic bits on my car. If I just prime and spray the bits, then the paint will crack off in no time flat

Has anyone got a suggestion for a home use paint plasticizer? I have access to a compressor driven spray gun now

 

I've heard that 'plastikote' is supposed to work (supple enough to allow some flex) but any time i've used it it's just been like any normal spraypaint except the finish isn't as good. I've just ended up using matt black halfords spraypaint (hence the black interior in all my cars).

 

Thanks, I'll try some experiments. The problem now is that plastikote doesn't come in deep highland green...