So earlyer today bertus52x11 posted the most clever idea. Aimed at people who only have use of their left arm - permanently, or temporally. His original idea was to add a thumb hook to the tripod connecter underneath, allowing the camera to be held steady with just the left hand.
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.
Using my drill on a high speed, I carefully drilled out one of the holes on my coat hook, I enlarged it so it was just big enough for the tripod screw.
Make sure you have it clamped securely, it makes all the difference when drilling metal.
Step 2: Leather Washer
I cut out a 3cm section of leather to sit between the hook and the tripod screw, it helps to give more grip.
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.
I took another section of leather, and wrapped it around the other section of the hook. Using some electrical tape a fastened it tightly around the leather and metal. Electrical tape stretches and makes it easy to attach the leather.
Step 4: Attach to Camera and Enjoy
Attache the hook using the tripod screw, my screw has a slot to allow one to use a coin to attach it.
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.