Left over sheetrock or wallboard makes great pottery drying boards. All you need is the board, a cutting knife and some duct tape. In this case I used white duct tape. Make sure you do this project outside away from your clay. Any plaster that gets into clay will cause it to explode in the kiln.
Let one side extend over the table. Hit the side extending over the table. The sheetrock drops in half right on the cutting line.
Flip the board over and cut the other side with the knife.