I know there were a couple other threads talking about painting your robot. I'm doing this with my RS Media using Rust-Oleum products I got at AutoZone. Thought I'd share my experiences.
I'm starting my test with the battery plate from the remote. This way I can practice a bit. So far, it seems that using primer either makes the primer and paint crack or is too grainy. So I don't know if I'm going to want to use primer. I have health issues which prevent me from doing any large amount of sanding, so I'm trying to find ways to not have to sand.
One thing is to spray a LIGHT coat over the area from about 12" (at LEAST) above the item you're spraying. Otherwise you get runs and stuff.
Also use THIN coats, don't put on a lot of paint at once. Figure you're going to need two or three coats (at least two).
Also I am going to try using a clear top coat. We'll see how it goes. I'll post pictures and stuff here as I go along.