Any shiny metallic silver base coat should allow you to get the anodized look from the Metalcast. I've never tried a flake base. Grab yourself an old fender and do a test run with different base coats.
When I did Sizzler, I initially thought that bare metal would be shiny enough. It wasn't. The skirt was shows Metalcast directly on bare metal, The guard has a generic metallic silver base. The base coat makes all the difference in the world. I hope the silver flake works.
Anything that is chrome doesn't need a base coat.
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