I am trying to engrave some of the 2 layer plastic to make some name plates. I have picked up some 1/16 inch thick material that is white and black. Now I am placing it on the table but it's not staying vary flat. As I am taking so little off, any materal that is not flat to the table will not cut right. What is the suggested way to hold this down to stay flat. The name plates are only 4x2 inches but the sheet is 24x48 inches. The table top I have is 24x24 inches in size and is made of MDF sheet. I have tried drilling some holes and screwing it down but this made this worse. Pls help. Thanks