I think you will find this lens is not the same as Leica, it is after all, a Tessar design, which has soft corners. I like the look, so it is a lens I use quite frequently.
You would have fun, I think, making a box paper camera. Set the focus to be something real close, for example 3 feet. Tie a string to the camera at the focus distance and hand it to your subjects. They would hold the string to their nose, you would prepare the camera for shooting, then they drop the string. You would have, a perfectly focused shot - and without any complicated mechanism.