First, build a box. We used scrap plywood and simply constructed the box using pocket hole joinery. You can also use glue and nails. The RYOBI cordless brad nailer is a great tool for this. Our box measures approximately 12 inches wide by 6 inches deep by 9 inches tall. You'll want to make your box according to which books you choose to use, as well as the height/depth/width of your bookshelf.