Had another play with my badge the past couple of days. I machined an aluminum one.
I first tried using gelcoat to colour it like my other badges but it doesn't stick to the aluminum and the colour came out in nice molded pieces.
So I gave it an acid etch primer coat and went at it with some Humbrol enamel model paints.
The colour sits in there as I originally intended so as long as it dries nicely I should be able to sand the surface back to aluminum and polish it.
Cheers
Stot