The powder coater will do it. They do that kind of stuff every day.
You want a guy who does custom auto, motorcycles and firearms. You do not want a job lot shop where your part will be mixed in with 300 washing machine lids or fifty lawn chairs.
A good coater can mask anything you want. Two tones, fades, metallic, crinkle, glow in the dark, lettering, clear coat, marble... doesn't matter.
https://www.prismaticpowders.com/gallery?tab=color
-Tim-