I agree. One thing I'd like to add: Sculpey (bakeable clay) is a great way to do that and cheap for the amount you get, but I'd give it a day or so after baking to cool fully and then
prime it before painting. My first few tries ended up glossy as heck, not matter how flat I could get my paint. I don't know if this has happened to anyone else. If it has, they may have an easier solution.
SteveM