What I think you are asking about is called "plastic canvas". It is an arts&crafts item used for yarn needlecraft. It is stiff plastic with holes for the waste to fall through. It is very washable, and makes keeping silkworms a breeze. I purchased mine at walmart, but believe it could be purchased at any craft store, or fabric store. For the smaller silk worms you will need to place a layer of screen fabric over the plastic canvas, or else the worms will fall through.