I don’t how you would use a shear but rather than buy a sheet metal
tool, consider a paper cutter. A paper cutter is a shear. A heavy
duty paper cutter is a heavy shear.
I have one that is light duty and have used it for a long time. It
effectively shears 18 gage silver and has no problems at all with
thinner material leaving a good edge.
I would suggest testing one by finding a friend and testing it for
proof of the pudding.
Ben A Harris