I have been asked by several baker friends of mine, how I spray gold on my cakes so evenly. I use a mixture of gold powder and Everclear (for gold dust I always use Crystal Colors by Sugarpaste)
Edible gold powder usually clogs up traditional airbrushes, so I bought this sprayer especially for metallic colors.
It closes air tight, so once I mix the gold (or silver!) with vodka, I can just store the mixture in the bottle as-is, and pull it out when I need it!
This works fantastic for full coverage on cakes, fondant pieces (like unicorn horns), and with stencils. Sometimes you have to play with the ratios, but for the most part, I just eyeball it!
For tiers covered in sequins or sanding sugar, it really helps! It's super difficult to paint a textured tier like that with a brush, and be able to get into all the crevices. Using the Preval Sprayer helps give it a shiny, even coat of edible gold with just one or two coats. (and very little waste!)
My affiliate link for the sprayer!