I've been playing around with rusting things for awhile now. I've found all sorts of vinegar and peroxide mixes that require 'cheap metal'....I'm all about cheap, but it takes a few weeks, and then it's a matter of not 'knocking off' the rust. I recently saw this spray.
It's textured and when it dries....it looks like rust!
When it first went on, it looked a little gray, but as it dried it turned brown and there are particles that make it look authentic. Yay for a quick fix to a life long problem....OK...not lifelong, but still...I like this spray!