HDPE (High Density Polyethylene) Plastic Sheet 3/8”- 0.375" x 4" x 8" White | eBay
1/2 in. x 4 ft. x 8 ft. White PVC Sheet Panel 190360 - The Home Depot
Amazon.com: AIMIMI ABS White Plastic Sheet 4x8 inch Durable Easy to Cut and Bend ABS White Plastic Sheet for Crafts Teams Hobby Industrial Mold (5 pcs),100x200mm,3mm : Industrial & Scientific