This is the back of a Leica M3. Just look at it! Could there be anything simpler? There are no controls; just an ASA indicator and a (world-beating) viewfinder. (There’s also a couple of flash ports but those can be safely ignored since no one uses them.)
I find the whole thing to be a work of art. The only thing better than looking at the back of a Leica M3 is looking through one.