Plasma cutters and oxy-acetylene torches are the preferred way to cut sheets of metal.
Acircular sawwill fit a 7 cutoff wheel.
Find an old and junky circular saw, as it wont last long due to the debris.
It sounds like a great way to start a fire so wed advise against this.
The blade on a jigsaw is too flimsy to cut sheet metal.
Always wear safety goggles and gloves when using a cutoff wheel.
