You can turn a cardboard file box into a real efficient filing system, with drop in files that slide with ease. First assemble a cardboard file storage box. The one pictured here has manila folders laid in it highly inefficiently. We're going to fix that!
Purchase a package of report covers. You are only going to use the plastic binding included in the package. Next slide on the plastic binding one on each side. Measure and cut a piece to finish it off to the end. Then drop in the files and you're done!