Hand shears, commonly used to cut small lengths of sheet metal, are available in three styles; each style is named to indicate its use. Straight shears cut in straight lines. Left cutting shears make cuts that curve to the left; right cutting shears curve to the right. Each tool is built similarly to scissors but with a much stronger shearing blade.
Squaring shears are available in a range of large sizes and may be pneumatically or hydraulically actuated. They are used for larger lengths of sheet metal that must be sheared in a straight line. These types of shears are commonly used in metal fabrication shops due to their cost, size and weight. When operating a squaring shear, the operator places the sheet metal between two metal plates, then activates the hydraulic or pneumatic mechanism to actuate the plates and shear the sheet metal.
Air nibblers are predominantly used in the automotive collision restoration field. They are handheld tools with three blades. Two blades are positioned above the sheet metal; the third blade is below the sheet metal. When turned on, the air nibbler's center (third) blade moves up and down, pressing the sheet metal between the two top blades. Another version of this tool has a single blade that is pressed through a hole at the bottom; it operates in a fashion similar to a paper punch.
Rotary tools, although not specifically designed for cutting sheet metal, may be used for this task when fitted with the correct cutting wheel. Use a metal-cutting reinforced wheel and cut at a 45-degree angle on the sheet metal. Ensure that you use eye protection to protect yourself from the loose material trimmed from the sheet metal.