After a new kitten walked all over a pastel drawing I was working on a couple of years ago and not only ruined it but tracked the chalk everywhere, I knew I’d need to cover my colored pencil drawings in progress even when I step away for just a minute. My drawing table is right next to a window that’s a popular bird-viewing spot! But I didn’t want to lay paper directly on the drawing surface. The perfect solution turned out to be a 20×30 piece of 1/2" thick foamcore, with 1" squares glued to the corners. It’s very light, very stiff (not even the weight of an adult cat can bow it), and the corners keep it up off the surface. When I’m working I keep it within arm’s reach.