I've painted dozens of brass locos in the past and it really isn't much more difficult that painting plastic. First you have to strip the awful heavy clear lacquer, but you can do that quickly and easily with plain old hardware store paint remover. And you might need to prime it, although Scalecoat I works on brass without a primer. This far it's about even up with plastic, or perhaps even a little ahead of plastic if you are stripping a factory painted loco, or the crap undecs that lifelike and bachman used to sell with a heavy layer of grey house paint rolled on. And don't get me started on undecs with glued in windows. The only part that is a little tedious, is whatever masking is necessary. Since all the details are soldered on, you have to be creative, since you can't remove them and resolder after painting. But really, if you find that too hard you shouldn't be painting them yourself anyway.