As an alternative what about an anodised finish in the colour of your choice.
Clearly there are loads of options. Unfortunately the efficacy of most of them will depend on how well the job is done which could lead to unwarranted bias.
I find it interesting that my petrol cap is just bare polished aluminium and while it does corode it doesn't take a great deal of effort to keep it reasonable. I did think about just doing that but chickened out.
