Me too with the under bar tank. I've been thinking about brass or copper from the pluming store. They have all the tube/pipe and fittings in the world and all I need to do is sweat it together solider and flux...... Tom in WV in'a VW.... PS my clutch slave cylinder went out to lunch. el crapola
I have been working on an underbar tank made from 3inch copper DVW pipe. I don't like the readily available flat sweat on endcaps so I working on hammering out rounded ends. It takes reapeated annealing of the metal because of workhardening from all the hammering. I thought about using a 3X3X11/2 tee rotated to one side to clear the top tube. Then use a threaded adapter for the cap or solder on a fitting off some other little fuel tank. I thought about splitting old copper toilet floats in half to use for the ends, but the metal is too thin.