This actually popped into my head related to the last question I posted about making an airbrush stencil.

How well would it work to airbrush on something dark, like a chocolate buttercream, fondant, or even just chocolate? I'm imagining the dark would show through, but maybe it depends on how dark and what it is?

You can airbrush on chocolate, but if you want a stand-out color like it would look on white, you have to use cocoa butter mixed in with color. If you just want to use luster dust, or give it light accents, you can use alcohol/luster dust combo.