thin polyethylene plastic sheet m st-HDPE high density . Thin to Thick Plastic Sheets and Small to Large Sheet Sizes. Plastic sheets range in various thickness, sizes, and even shapes to suit the application. From 0.06 inch to 6 inches, with some custom sizes available, mmon thicknesses range from 0.25 in, 0.5 in, 0.75 in, and 1 inch up to 6