blind cup_socket-plug connector

On board of ships are many electric sockets. They need blind cups to be hermetic, and this is a thing which often dissapear. Here is a solution. We could use it also to blind valves with air or water.
On the ships we make shopping in many different countries - hermetic electric plugs have often different threads and forget about watertightness. But we can solve it.

Libraries used - threadlib.scad by Adrian Schlatter