Amazon.com : Corrugated Plastic Sheet for Indoor and Outdoor Use - 3/16 Inch Thick Poster Board, 24x36 Inches - Pack of 2 Black Plastic Board Sheets - Waterproof Coroplast Sheets and Lightweight
Corrugated Plastic Sheets 4 x 8, Sheets 4'x 8'
12 Pack of Corrugated plastic 4MM white Sign Blanks - 24"x36"
Amazon.com: (10 Pack) Black Corrugated Plastic Sheet 24" X 36" Horizontal : Industrial & Scientific