Received my Northern Tool fenders yesterday. (Pretty surprised at the quality for just 25 bucks each.) They say they're paintable right out of the box, because of something they do to the surface.
But do you think that's REALLY true?
I was thinking of using that exterior Flex Stone stuff in a spray can. (Rustoleum makes one, too.) It gives like a textured sand or stone finish, which you then overseal with their protectant coating.
Think it'll hold up?