These photo steps show that it can be done using a utility knife.
Cut sheet metal without curling.
It involves a bit of more work but the good thing is that most of the tools required are very basic.
The method you choose to cut sheet metal depends on the thickness of the metal and the type of cut you plan to make.
If you use metal shears to cut thin sheet metal such as duct metal it curls and can be difficult to flaten properly.
To cut straight lines use an electric saw.
Among others the most basic manual tool that you can use is a tin snip.
Start by taping both sides of the sheet metal directly over the line you want to cut and clamp the metal to a work station so it doesn t move.
The illustrations are for a small bracket but i have cut 3 foot.