HDPE (High Density Polyethylene) Sheet, Opaque White, Standard Tolerance, 3/8" Thickness, 6" Width, 12" Length by Technology Island (6 X 12) 10 left in stock. Acrylic Sheet Black Cast Glass (Set of 2) 12" x 12" Long Panel 1/8" Thick (3 mm) Plastic Board with Protective Paper for Signs, DIY Display Projects, Craft.