Have used this stuff in the past, widely available & reasonably priced
Achieve effortless and faster spray painting with PlastiKote Twist & Spray, featuring Easy-Spray Technology for faster, cleaner application. With its premium finish and versatile use on various surfaces, enjoy hassle-free painting with no recoat window, thanks to its Twist and Lock cap mechanism.
plasti-kote.co.uk
A wide range of colours to chose from.
In your situation, I’d give the stock a proper clean to remove dirt & grease/oil then knock it back with a scotch brite pad (& fine grit paper if those little dots are raised?) then use panel wipe before spraying a base coat & you should be good to go with your sponge after that.