🔑🔑🔑 we now stock 'Key Lock Switches'! These mechanical switches don't use a button, a lever, or a magnet to open and close the contacts. Instead, a literal key is used. This low-cost but effective key lock switch is nice and compact: you only need to drill a 12mm / 0.5" diameter hole in your mounting plate.

Insert the 'bike lock' style key and rotate it one turn clockwise. Now, the two contacts on the back are electrically connected and locked. Rotate it back counter-clockwise to disconnect the switches. This makes for an excellent 'On-Off' switch that requires the key to activate. 

This key lock is 'momentary' style - because you cannot remove it once it's turned On. You have to rotate back to Off to remove the key.  where the key is removable.

Please note:  - each key lock order comes with the same keys. And it isn't hard to pick this lock, either. Think of this as a fun interface or minimal security setup where you aren't concerned with a skilled adversary.