Hidden Door Lock 

What sensor did you use? I'm looking to do something similar with a bookshelf door into my theater.

What I want to do is have something like this installed in a floating shelf with a drop down bottom with hinges that hides a pistol or other valuables. I want to have an object sit on the shelf that keeps it locked unless it is moved, like you do here. It only has to be strong enough to keep the shelf from opening by itself. Is there a less complicated way to do this? Cool video BTW.