Mark the required dimensions on the surface of the sheet using marking tool and straightedge.
Cutting copper sheet with a torch.
Cutting your own copper shapes can be easier than you think.
They look like big scissors and work the same way.
For higher gauges meaning thinner copper you can easily do it with standard hardware store metal snips.
Measure the dimensions needed with tape measure.
Begin cut with metal cutting sheer.
Cutting slower will also give you plenty of opportunity to blow away the bits and pieces of copper and dust caused by the cutting process.
The sheers handles are brought together to cut through the sheet.
Elevate and support one edge of sheet with free hand allowing entry point for cut enough clearance for metal cutting sheer to proceed.
Once the copper sheet has been marked where it needs to be cut the sheers blades are positioned on each side of the sheet as would be regular scissors when cutting paper.
Take your time and let the cutter work its way through the copper for a straighter and even cut.