All credit for this idea belongs to bertus52x11, I just modified it slight, mainly by chance.
When I saw his project, it instantly reminded me of a coat hook I had found recently, I made a comment to point out this fact, and said I would have a look and maybe post a picture. So I drilled one of the existing holes so it was big enough for a tripod thread mount. I then added a small circle of leather to give more depth, and added grip.
Once I had mounted it, it worked just as bertus52x11's idea. Allowing me to hold the camera, and activate the shutter with one hand. I was about to start sawing the extra protruding section off when I realised that it could easily be modified into a mouth grip, partly inspired from this instructable.
I then wrapped the mouth grip with another section of leather, and taped it on. I can easily support the weight of the camera with my mouth for a period of time, enough to use my left hand to pop the lens cap on, or even change the lens (though one would need to practice that.)
I am entering this into the Health by Design contest, but because it is so similair to bertus52x11's idea, the main reason I am entering it is so that if this instructable wins anything the prize will go to him, giving him an extra chance of winning! Be sure to check out his other projects, a lot of them are simple ideas, but the kind it takes a genius to think up.
Step 1: Drill the Coat Hook.
Make sure you have it clamped securely, it makes all the difference when drilling metal.
Step 2: Leather Washer
Once I had cut out a circle, I then punched a hole in the middle, I then put a couple of slits either side of the hole to allow me to easily push the tripod screw through.
Step 3: Mouth Grip.
Step 4: Attach to Camera and Enjoy
Once attached hold the camera upside down, and place your thumb in the hook, you can then press the shutter using your small finger.
If you need your other hand free for a moment, say to pop the lens can back on you can easily hold it with the mouth section.
I would recommend using it with a neck strap of course.