For years, I’ve been using stackable file trays from Ikea to keep my sandpaper organized; inevitably, the trays would get full of sawdust, and they were too shallow to read the grit value, so eventually the values would all get mixed up, so I couldn’t tell what I had. Switched to an an accordion file today—so much tidier, easier to read, and takes up only a tiny bit of space in my cabinet. I also learned that I impulse-buy a lot of 600 grit.