Acrylic metallic GOLD paint shouldn't stain, but it's not my area of expertise. Some acrylic paints do use stains as the coloring and would stain. I've never used it, but it ought to work, and is probably less likely to cause allergy issues than latex paint.
I've used latex paints with some success, but it takes a considerable about of time for the paint to cure, and it sticks to itself if its not fully cured. Limited color range, too, and I have NO idea whether you could air-brush it or not.
For a real metallic sheen, Mehron (and I suppose others) sells a powdered make-up that, when mixed with their liquid make-up base, can be applied to give a not-too-far from gold leaf effect - i.e., a gilded subject. It comes in gold, silver, copper, bronze, and probably a few other shades. Probably can't be sprayed on, though. And it's designed to be a cosmetic.
I seem to recall some recent work posted here that was done with temperas. (Not by RobArtLyn.) Look back a couple, three months.
Good luck, have fun. Looking forward to seeing your results.
"Keeping shooting will do more for the excellence of your photography than most any camera will!" JimmyD, PGS Extraordinaire.