yes, i painted mine outside, tried to do it in thin layers, done it in like 3 coats, and the last coat still wasnt atall flat, i used some halfords rubbing compound, to flatten it which did work and then polished it up with tcut, looks good apart from it went very thin in a couple of spots where you can see primer through it!!!
aside from that, about 3 days later a seagull sh*t on it and the marks still there