A drill is a handheld tool that cuts through sheet metal via the rotary motion of a replaceable drill bit. The diameter of the drill bit will determine the size of the hole. A drill bit known as a hole saw, essentially a round saw blade, can create larger holes. The edges of the drill bit are serrated, which pierces the 20-gauge sheet metal with its rotary action.
A shear consists of a long blade used to penetrate and cut metal. Shears can come in many types, from foot-operated shears to hydraulic or pneumatic shears and manual shears. In foot and manual shears, the individual produces the effort that causes the shears to pierce and cut the 20-gauge sheet metal. Hydraulic and pneumatic shears release oil or air between pistons that stimulate the cutting action. Many types of shears are appropriate for different types of sheet metal gauge. Check with the shear manufacturer to inquire whether the tool can cut through 20-gauge sheet metal.
Almost any type of saw can cut through 20-gauge sheet metal. A saw is a tool with a serrated blade. The blades are normally relatively large to accommodate thickness and size of the sheet metal. Some examples of saw tools used to cut through sheet metal include hacksaws, table saws and circular saws. A hacksaw has a long frame and fine, serrated teeth; the operator pushes and pulls it back and forth to make cuts. A table saw has a circular saw blade driven by electric motor to cut through the surface of the sheet metal. A circular saw cuts via a rotating circular blade.
Tin snips resemble scissors but are much stronger. While most are manual, electric and pneumatic tin snips can make cutting sheet metal easier. Tin snips produce long and straight cuts. You can lift the sheet metal away from the cut as you cut with the tin snips all the way down the sheet metal to produce a straight line.