I think the Metalcast was used on several build off bikes, mine included. I've also used it on a number of other bikes, and I've used it in most of the colors that it's offered in. I can tell you this - they claim that it is intended to give polished or plated metals an anodized look, but I don't think that there is any special formulation to actually make it adhere to chrome plating better than any other paint. Like any paint, it adheres best to a surface that's been prepped for paint, by scuffing or whatever. It's tough to do that with chrome effectively, and doing that on polished aluminum destroys the polished surface. Consequently, when you do put it on these surfaces, it is highly scratch prone.
On my build off bike, I sprayed the Metalcast over bare steel and aluminum parts. I avoided doing any polishing. In fact, I wirebrushed and sanded them a bit first. That also gave the parts a bit of graining to the surfaces, which shows through the paint. They do sell an "Adhesion Promoter", which is essentially supposed to be a clear primer. But in my experience, it doesn't help much on polished metals. The paint system works best if applied over Duplicolor's Ground Coat base paint. It has a heavy metallic silver finish, and sprays on rough enough that you don't have a scuff sand it to apply the Metalcast. If that is, in turn, applied over their self-etching primer, it makes for a pretty durable finish, at least as spray can paints go. I always put a clear coat over the final color layer; lately I've been using only the urethane-based SprayMax clear. Taken all together, you can get a pretty good looking, reliable finish. It might not be quite automotive grade, but it's good enough to have people compliment.
The trickiest part is getting the color to go down evenly, since it does darken with coats. That does allow you to make it darker or lighter, depending on preference, but it's tough to match other parts to. You can, however, "tune" the shade by applying over different color base coats. You don't have to use the silver, I sprayed the purple (which is fairly red-tinted) over a light bluish purple base to get a bluer shade of dark purple for a result. Just watch what types of paint you mix with. Metalcast is enamel based, IIRC, and won't play well sprayed over laquer.
