Admittedly this is a bit of a contraption, but it has worked wonderfully. I type a whole lot at work, and over time tried a large number of ways to get rid of hand and arm stresses. Eventually, having got my positioning right, I found that an enormous remaining stress was my mouse and most especially the left-click, which we all do a very large number of times per day. So I bought this:
www.clearlysuperiortech.com/cst2545saw
from here:
www.ergoguys.com/pctrac-tracball-w-superiorx-button-control-softwar.html
which is a nice big trackball for multiple fingers or palm (I found the small ones worse, not better, than my mice), and more importantly, those three jacks. It’s one jack per mouse-button. Originally I had thought to bring left and right buttons to foot, but I ended up doing just the left, which has done me just fine and dandy. I initially bought two of these:
www.clearlysuperiortech.com/external-buttons
similarly:
because they were not expensive; I destroyed the first one (with my foot, they’re not exactly designed for stomping) in a few months, which gave me enough time to figure out what to do. Soon I received a marvelous inspiration, and looked into a “ribbon switch” or “tape switch”. These are industrial components used on conveyor belts to detect items, and safety applications where one wants to stomp on something to get it to stop. So I bought one of these:
www.tapeswitch.com/store/proddetail.php?prod=1100
in the one-foot length to save at least a bit of money, with the aluminum channel for mounting (I think this is needed), mounted it on a 48”×6”×3/4” piece of wood, had my friendly neighborhood electronic musical instrument shop solder me a 1/4” mono phone plug on its wire, ran a long wire from that plug to the 1/8” jack on the trackball…and it works!!!
There is a bit of technique I have had to learn for it to work easily, a kind of bounce of my heel to mimic a rapid left-click; and I do sit now with one shoe off, tread does not help; but I have zero pain in my hands after work these days, which is quite the joy.
Admittedly the trackball and ribbon switch are not inexpensive. On the other hand this trackball looks and feels, inside and out, that it will work for decades, and the ribbon switch is an industrial component, so unless I mounted it badly it will do for a nice long time. The only thing I might have done differently is to get a longer ribbon switch, probably two feet long, though that is luxury, not necessity!