Since people are asking, the rust stuff I’m using is called "Sophisticated Finishes" from Triangle Crafts. It’s the iron metallic surfacer and the rust antiquing solution. (They sell ’em together or separately.) It’s got a tacky cherub on the front, but so far, it’s working quite well. Results aren’t instantaneous–most of mine are sitting overnight, and require multiple thin coats of rustifier, and you may have to clear-gesso surfaces first to get it to stick, but the results, when done, are really rusty.