I masked off the dome today leaving only the little section around the rear PSI that is supposed to be blue. On the front PSI, there is a cut out, outer dome piece that mounts over the hole, but on the rear one, it's the inner dome itself that is painted inside the picture frame piece of outer dome. Someone called this the "perfect circle" because you have to cut this one yourself and it has to be done exactly right--no help with the laser cutter on it. I think I used a slightly smaller hole saw and then rounded it out with a file. I have been surprised at how workable aluminum is on the project--I didn't think the perfect circle was that hard to create, or at least to get it perfect enough to suit my eye.
I also masked off the top ring of the dome mounting ring because it needs to be blue. I came up with a little trick here. I didn't want to get blue paint down in the groove between the rings, but just hanging tape over the edge wasn't going to seal it up enough. So I got some plumber's tape off my bench--the super thin white stuff that you put on threads for pipe fittings--and I wound that around the dome ring a few times pulling it tightly until it filled up the groove. Then I taped it off so that the tape just overlapped the plumber's tape. That way the plumber's tape would keep paint out of the groove. And the blue would have an edge right at the lip of the groove. The tricked worked well to keep paint out. Here's the ring primer with self-etching primer. I also sanded both sections down to 400 grit or more.
After the primer dried on these pieces, I gave them both a light coat of cobalt metallic blue, let that dry for an hour or so, then I put a medium wet second coat on. After ten minutes I layered on the blue anodized. They came out pretty well although I got a scuff on the ring and had to go back and feather it in and paint a bit of touch up. The scuff seemed to just be into the blue anodized layers. So I let it dry for a day or two, then I very lightly and carefully used some 400 grit on it to feather the edges down and try to get it to blend in. Then I hit it with a couple more coats of blue anodized. That made the blue anod. heavy and less of the metal flake came through, but overall I think the results are good.