What do you do for a gas cap when you scratch build a tank? Well, you scratch build the cap of course! This is actually about the third incarnation of a cap. It took a while to R&D previous versions, figure out what looked best, what worked, etc.
It's Al-You-Min-EE-um, , Danny machined a nice groove for the o-ring (after the previous version flew out of his lathe, we started with a flat piece and machined the groove first), and we hand filed, sanded, and grooved the rest of it. Then, we made a mounting tab, drilled it for a rollpin, drilled the tab, contoured it, made sure the o-ring woul seat to the flat steel on the tank, welded it all up, clearanced it, etc.!!! A LOT of work for a piece that most people won't notice, but it is one of a kind for SURE!
The view from above. wow, this is really insane, never seen a cap like this, hope people will appreciate it-- Still need to drill the vent holes and holesaw out the opening in the tank. And, HOPE a gas nozzle fits inside since we were limited on space!