Chaos Renegade - back on track

Minds turned back to the Chaos Renegade outfit, that i really must get finished.
Nearly there with rusting up the front now and soon i'll be flipping it over to work on the rear. Biggest thing to do is to disguise the ends of this roll of foam that is an air tank.
Was thinking of some sort of round plate affair, with a nice grill detail or somesuch in the middle to add interest. Thinking something from the cooker/air-con section of the DIY store.