I painted my car with Kirker single stage. It's online, and cheap. For some areas, like jambs, I just thinned it and sprayed it without activator. It still dried rock hard and is holding up fine. Just didn't want to have to deal with the hardener and the poison vapors. I didn't try it, but since there's no hardener, I think I could have mixed some thinned mix up and kept it around and used as needed for a while so I didn't have to have everything ready to go with an activated mix.