Soundproofing Closed Cell Foam Mat Blocks and Absorbs Sound (Peel n' Stick) - Create a sliding panel for behind the bookcase (any look you want), that will cover the door. We can then put this material on the door side of the panel, where it won't show. It is dust resistant. Bookcase only needs to be as deep as your deepest book. Can also be used around your compressor vacuum.