“Egg crate” is a white, plastic light diffuser made for recessed ceiling lights. This product typically comes in 2′ x 4′ sections and can be found in the ceiling tile department of your local building supply store. Cut it by reaching into a cell and breaking off the divider with a needle-nose pliers. (Be sure to use eye protection for this process.) The most obvious use for egg crate is in a downdraft sanding table. However, I also have found it useful for lightweight shelving, racks for drying recently finished parts and as a separator when sticking lumber.
-Dana Craig