Something Completely Different.

It's not a lock, it destroys the contents of the box. There is no risk of injury.
But if someone attemps to bust in, I want the contents destroyed.
By the way, the coherer seems to work, in that it usually shorts when you fire the marx, but it also shorts due to lesser disturbances. This could be a great inconvenience.
In reply to a couple of previous questions, yes, it is military or something, and yes, the batteries and solenoid do survive.