Crumble-Friendly Switched Battery Box
3 AA battery box with Alligator-clip-friendly connection points and built-in resettable fuse to protect against short-circuits. The on-board green LED shows when the switch is on. A red LED will light when the fuse has been tripped (most likely due to a short circuit somewhere among the connections).
Check out these guides from Crumble's manufacturer to get set up and programming!