2064 Gray, Transparent, Acrylic Sheet, 6MM (1/4") Thick, 12" W x 12" L (Pack of 2): Amazon.com: Industrial & Scientific
Amazon.com: 2 Pack of Clear Plexiglass Acrylic Sheet 12x12 Inches, 6mm (1/4 inch Thickness) Unbreakable and Lightweight Substitute for Glasses, Great Use for Sneeze Guard, Shield, Greenhouse, Poster Frames : Industrial & Scientific