Wanted: A Good Footmouse
One obvious solution is a foot mouse, a device that would let you control the mouse with your foot while leaving your hands on the keyboard. A little online searching located two such devices, the NoHands Mouse from Hunter and the Foot Mouse from Bili. Both are expensive, and the one comment I could find by someone who had actually used them both was that the better of the two, which costs about $300, had sufficiently bad quality control so that the user had gone through four of them in four years. I also found one other device which used the head instead of the foot, via the combination of an infrared camera attached to the computer and a dot visible to the camera that you could attach to your hat, glasses, forehead, ... . A detailed review of that one concluded that it was inadequate for computer gaming.
I'm not an engineer, but I don't see why one could not design a reasonably simple foot mouse—essentially a larger and sturdier version of a standard mouse built into something like a slipper—with a production cost not much more than that of an ordinary mouse. Such a product would be useful not only for those with physical handicaps, the market that the products I looked at seem mainly intended for, and gamers, but for anyone who routinely uses both mouse and keyboard and finds switching between them inconvenient.
Am I missing something? One possibility that occurs to me is that the foot may not be adequate for the purpose. We use our hands for tasks that involve considerably finer control that what we normally do with our feet. Perhaps the machinery of nerves, muscles, tendons controlling the food doesn't permit the sort of fine control needed.
But I would still like to try it. Perhaps a slipper, a mouse, and duct tape?