Some of the humbrol metal paints stand a polish, you know, and that brings them up 'looking like metal'.
I have 'Steel' I think it is. It's from a little sub-set of the humbrol range. That dries matt until I polish it with a cotton bud or something and it then shines and DOES take on a more realsistic 'metal' colour. However, I also have gunmetal, and brass, from the normal range and the Gunmetal doesn't!
The brass was bought recently and have yet to try a polish. [just tried my brass, it finishes with a 'bitty' texture, same as you? It's the right colour but that texture is bad for a supposed metal finish. Tried a polish and hmmm...it did look a bit shinier but didn't remove that texture.]
HIHs
Oh, my other though was gold leaf... or they also do a pueudo gold leaf. I don't know how practical that would be?