I'm not afraid of sanding and filing. My 1:1 R2-D2 has quite a few resin detail parts and some of them required some elbow grease. I usually use JBWeld to fill gaps and air holes. I have a set of needle files a lot like the one in that link. They come in VERY handy for small resin work.
I used auto paint for my R2. There isn't anything that has the depth and shine like auto paint, I think. The only things I don't clear coat for him are the silver/aluminum things because it turns it to flat grey. Everything else was clear coated about 4 times.
