Powder Coating

i got my bumpers from ora and they were powder coated,looks ok for a couple of months but cracks appear on the edges and it peals off like wall paper,,looks crap when u try and touch it up,
i just had mine sandblasted and painted it myself.

smooth hammerite and a brush

We have a Powdercoat magic DIY set up which is great for small stuff- brackets, alloy casings ,bits of plate. Made some wing top protectors for the jeep about 4 years ago and they are starting to break up on the leading edge, commercial stuff might go on thicker.
Have found curing smoothrite painrted stuff in a warm oven does the same sort of job- if doing your bumper you could possibly get it ina hot boiler house, not recommended touse a food oven for paint/powder as it tiants your pies;)

Rustoleum paint is good - painted an entire fibre glass tub using a roller and was surprised at the good quality finish ,we used an adhesion primer and 4 years on it is in decent shape, have seen other painted fibre glas where a blast with the power washer and it all strips off.
We did buy some white meta lpaint from Screwfix a while back which was acetone based - vile smellworse than usual solvent based paints but it went ont really thick and was very tough ideal for wheels, not sure if they stilll sell it but worth a look.
atb
Mike

Finally found a picture of the Minor bootlid I painted in Rustoleum.