Well I said I started on a few side projects over Xmas, so the first was tinkering to get myself an fuel flap. Whilst I'm not sure how it will actually function, I continued on in blind faith and ignorance. So a small square was cut, and put through my mini English wheel. Wheeling in one direction gives the curve in the panel.
So I cut some 50mm discs from 1.5mm steel, I might need a slightly larger disc but I didn't have a bigger hole saw. The hole for the fuel flap is 60mm, so with the door skin I have a fuel flap of 52mm which leaves 4mm gap all round. I might weld a small wire around the edge of the disc if I want to reduce that gap.
However one disc is for the base to hold it too the car, the second is to hold the flap skin. So I'll just the hole saw to cut the centre out.
Right now id be happy to just have it held closed with magnets. It's really just to hide the fuel cap, as long as it looks online with the rest of the body on the car