This simple & inexpensive modification has many benefits over using the glass bed alone. Metal conducts heat better than glass, and eliminates cold spots on the bed. This cookie sheet has a non stick surface which enables prints to come off easily. You will still need to use hair spray or a glue stick, but it's able to be cleaned very easily compared to the glass bed. Bed liners aren't necessary. The surface is smooth, scratch & bubble resistant as long as you use a putty adhesive under it. An oscillating multitool is used to cut it. A wide jaw sheet metal or welding pliers bends the metal corners. A file makes the rough metal edges smooth.