Anothe fun fact: these are perfect cases for small electronics projects. They have a small and a large compartment, where you can fit e.g. an ESP or Arduino Nano and a battery in the big one, and a click switch and an LED in the small one. The latter has a flexible lid, so you can work the switch just by clicking the lid. Completely innocuous WiFi snoop box, or FastLED controller, or a million other things.