Mission accomplished. Mostly. My goal this weekend was to chop up the Tiger Cub oil tank and increase the capacity. Last week I made an mdf mold of the tank shape, accounting for material thickness.
Then Friday I took my time, measured, carefully cut the back off the oil tank. And then I cleaned it all out.
Saturday I woke up, made a cardboard mockup
I finally got to use my air powered sheet metal shears. I tack welded up the sides and spent a lot of time massaging the metal to shape. The back actually tapers to a smaller shape so it made fitting things a little difficult.
I need to finish welding the tank up. I actually might try brazing it. And then I need to add some sort of cover to the side to make it look seamless.