I started looking at the hand support options today. I originally was considering using silicon coated modeling clay, but I don't think it will be quite stiff enough. This morning, I grabbed a couple of latex medical type gloves and filled them with some wet sand. Obviously, the laytex gloves are a temporary solution to play with. The first one had way too much water in it and is too squishy. On the second one, I went very sparingly on the water and it turned out much better. It makes for a moldable blob that is very firm that should serve as a hand support. Eventually, the buttons and trackball will be attached via velcro around the front and side portions. This would allow the end user to rearrange the trackball and buttons in any order they want and custom fit the support to their hand. It should allow maximum flexiblity and comfort.
As you can see on the breadboard, I have three wires arranged as touch sensors (one with a quarter attached) for left, middle and right clicks. I also got the scroll wheel functioning with the rotary encoder there on the board. Lastly, there is a button and associated tri-color LED that is used to swap between the four user selectable resolution modes inside the optical sensor. This essentially controls how much movement the pointer makes relative to the amount of movement you put into the trackball, allowing for either lightning fast moves or very slow accurate moving. It operates somewhat like what happens when you change the gears on your bicycle.