The clip idea isn’t mine, this design using it is. These boxes are 10x20x6cm and are laser cut from 4mm MDF. I use them to hold small parts when I’m making lanterns etc. The clip mechanism is very satisfying. The box is ready for use immediately — no waiting for glue to dry.
Update: If you have access to a laser cutter, you can make these boxes/trays using the download project in my Etsy shop.