How can we make 1000 litre Custom Fuel Tank of Heavy duty Truck with the sheets of metal

In a process which would dates back decades, steel tanks can be fabricated by welding strips of mild steel together, forming a large hollow container. Such tanks are typically square or rectangular in form. Alternatively, a steel strip can be rolled, before being welded to 2 pre-manufactured ‘dished’ ends, creating a tank which will have a circular or ovoid cross section.
Steel tanks are usually available in a much greater range of sizes and capacities than plastic tanks. Some steel tank manufacturers also offer a bespoke build process, allowing you to effectively design your own tank.