I don't use 5C collets often, so I like to store them away. I made a tray for storing 10 standard 5C collets lying flat, with sealed bottoms to keep any oil dripping under control. I'm planning on adding some kind of rust preventing liner eventually. This tray is also stackable if you want to print multiples. There are cutouts for 12mm or ½" labels on the top (to identify the collet sizes) and front (to identify what collets are in the tray when viewed from the front).