Suggestions on How to Paint This

I have a bunch of the non color title belts (all gold) that I'd like to paint / customize to look more like the real belts.

With the belts being so tiny, what are recommendations to paint in very small areas and not make a mess of it?

For example, this belt in the link was painted and I dont know how they painted the black around the letters and stars.   I tried a toothpick with a microscope, but the toothpick seems too big to be able to paint just that black area.

ibb.co/sV07cDt

I'd love to know how this can be done...

Thanks!