To cut the material I used a circular saw and a cordless drill with some spaded bits. Be sure to use two hands with the drill, because if you slow down and the bit catches in the plastic, the torque will twist the drill out of your hand.
No matter what type of polymer material you use, make sure to get something that is impact resistant, abrasion resistant, chemically resistant, and ultimately strong. I would recommend Polycarbonate (lexan), ABS, or UHMW Polyethylene, and many other types of acrylates. If you get a polymer material you'll surely want something thicker than the metallic counterpart. 3/16" is the thinnest I would go with any polymer material