Cut along your measured line with tin snips.
Cutting galvanized sheet metal with plasma.
Use 1 hand to lift 1 half of the sheet metal while using your opposite hand to cut along your pre marked line with slow gradual cuts.
I have an application that would lend itself to a plasma cutter i think.
A handheld cutting tool fitted with a metal cut off wheel will easily cut through sheet.
We cut galvanized steel ranging from 20 to 10 ga.
The zinc in galvanized steel can react with moisture from the scrap metal creating a highly flammable stream of hydrogen that shoots out when the outer layer of galvanized steel is cut.
Jigsaws and metal cutting band saws are more work but can make most cuts in light to medium sheet metal.
How to join galvanized metal without melting the galvanized coating duration.
Prevent an explosion from such a reaction by treating such cutting as if high pressure gas is inside the compartment when you start cutting.
Cnc plasma cutting sheet metal 50 amps duration.
The process of using tin snips is very similar to using scissors.