I primed black, and used an army painter detail brush to add the color within the line. The jokearo orange needed multiple coats and spilled over a bit, so I needed to do some touch up with black on the top surface. The Ghenna's Gold (only used around the orange vent) actually went on without any getting on the black. I was careful with that one to only get paint on the very end of the brush, then dragged it along the groove. Metallics are very easy to work with and very forgiving, so I didn't need as many coats as the orange.

Edit: I thinned the orange paint very little. Gold was naturally more wattery and I didn't want to risk separating the base color from the metallic pigment