I made it from a 1 mm iron plate. After the suitable measurements and cutting, I used the power hammer, english wheel, a little shrinking at the edges, then the final touch was TIG welding. So I'm ready to call to life any fuel tanks or re-design an old one. The price is like 250 €, depending about the form and complexity.
These are hammers with different heads covered with tick leather. You get some spare leather strips as a present, too. The hammer is suitable for smoothing soft metals, thin sheets and buckles. Price: 24 €