I'm going to try my hand at repainting a 1/18 scale model. I recently got a model, a UT Porsche (obviously) GT2 in silver. It had the hard to find "updated" painted wheels so I may have overpaid. It arrived, from the Netherlands, in bad shape despite the seller claiming it was "like new". In any case, I got another silver one (also claimed to be "like new" and wasn't but that's not the point), with the old wheels and the missing brake calipers, for cheap. Figure I will practice on the cheap car first. Who knows, I could end up with 2 good, custom painted GT2s! With one still missing the brake calipers....
I think I can rip the cars apart if I'm careful. My concern is replacing the decals, mainly the "911 GT" on on the rear of the model. I can live without it, though, and the Porsche crest will be easy to replace. Should be fun.