Second mouse. Doesn't have to be fancy at all. Since I trained myself to be "ambimousetrous", I keep two mice attached to my work computer (one on each side of

Second mouse. Doesn't have to be fancy at all. Since I trained myself to be "ambimousetrous", I keep two mice attached to my work computer (one on each side of the keyboard) and switch back and forth throughout the day. It significantly reduces the load on each hand and guards against RMS. Switching hands for mousing is basically subconscious at this point.