Metal Signs can be composed of aluminum or an aluminum composite such as Max Metal. Aluminum composite signs are constructed of aluminum on the front and back, sandwiching a middle piece made of a coroplast, PVC, or a plastic composite. For the aluminum composite signs, the cost varies depending on the size, thickness and what material is in the middle. The material is more rigid than PVC and lighter than MDO Wood, which makes it easier to handle. These are great for exterior signs such as "No Trespassing" signs, parking garage rules/directional signs, safety signs, and have even been used for monument signs.