Where I work we have a safety door with an unlocking mechanism.

A long time before I started work there, the door was locked and anyone that wanted to enter ringed a bell, and someone inside would press a button under the desk in order to unlock the door. This was all working fine until it was needed to do some renovations on the floor of the room. The cables to all the buttons under the desks were cut and the door stayed open during work hours ever since. The trouble was that some times we have team meetings in this room and the door needs to be closed. So if any one rings, one of us, has to go and open the door. Joining some laziness with the excuse to build something, this project has born.