This would be for a 1/12 scale model. I think the emblem would be approximately 3/4" in width. I`m not too concerned about the material used as long as I can glue it to the model and paint it with chrome paint. Do you happen to have a recommendation on who could make that?
Plastruct`s diamond plate is way over-sized if you go by the scale numbers they claim. I used the 1/48 scale plate for my truck below, which was part number 91684. I tried the 1/32 scale stuff, and that just looked way to big. Hope this helps!
I have used Duplicolor clear over Duplicolor, Tamiya, and Testors Custom Lacquer series. In fact, the Big Scale Beauty car in my sig was Duplicolor Black with Tamiya French Blue topped with Duplicolor clear, if memory serves me. The only issues I have had was in some instances, if I would use Duplicolor colors for stripes over Testors lacquer lacquer, sometimes the Duplicolor color would "pull away" from the masked line, and it wouldn`t be straight after applying the Duplicolor clear.