Channel Letters are custom-made metal, acrylic or plastic letters that are commonly used on the buildings of businesses, restaurants and other organizations for exterior signage. A standard channel letter is a 3D graphic sign element. Its channel is fabricated from sheet metal, most often aluminium since it will not rust. A flat sheep of aluminium is typically cut on a table by a computer-controlled router. A trim cap border is applied to its edges which gives the letter dace a finished appearance and creates a fastening surface to attach it to the letter can. When illuminated at night, channel letters dear the eye of passers-by. Cannel letter versions include front lit and back lit.