Anne use whatever paint you have, thin it down to a very runny consistency. Flat black works well for those U-joints, for example brush some into the crevices let it flow, and you will see start to fill the voids it make take one or more applications, wipe away any excess with some of the thinner. When I do this, I like to use a laguer as a base, then an acrylic for a wash. Then if you dont like it you can just wash it away with some water, and start all over again.