Re: Fuel tanks
Be very very careful trying this. Unless you have a good understanding of metal, welding and the pressures you'd be working with, you could be injured. Hydro forming metal is a job best left to those with the knowledge and the proper equipment. Simply pumping water into a closed vessel without careful engineering could produce a very effective 'pipe bomb'.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"