The search for a more er­gonomic wrist po­si­tion has led me to ex­per­i­ment with up­side-down mice. My first at­tempt was to fill a tiny, 2.4-oz mouse with sev­eral 2.02-lb–pull neodymium mag­nets:

Upside-down magnetic mouse

This worked, but it was dif­fi­cult to find the right bal­ance of mag­netic force ver­sus free­dom to slide. Too many mag­nets caused fric­tion to in­ter­fere with po­si­tion­ing; too few al­lowed the mouse to oc­ca­sion­ally fall dur­ing rapid use. I suspect that mag­netic ball bear­ings may be re­quired to si­mul­ta­ne­ously per­mit suf­fi­cient up­ward at­trac­tion and free­dom of lat­eral mo­tion.

I next tried an in­verted touch­pad fash­ioned from an iPod Touch run­ning Log­itech’s Touch Mouse soft­ware:

Upside-down iPod Touch mouse

It was dif­fi­cult at first to get used to the in­verted track­ing be­hav­ior, but I learned to love this arrange­ment. I ended up us­ing it for three months, only to stop when I moved on to new work and the Touch had to stay be­hind.