What sticks to matte black iPhone cases?

I have a matte black iPhone 5s case, and I'd like to personalize it. The issue is, i don't know what i could use to write on it and make it stick on. I don't want to spray paint it because the writing/designs I'd like to put on the case require a much more precise utensil. I don't know if i could use gel nail polish?

Metal

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