Back in the spring I tore a ligament in my left ankle. When my ankle is sore this makes upshifting painful. I decided to try to make a heel shifter to ease my pain.
My first attempt was not successful. I removed the 6mm bolt, retapped it to 1/4", and used a 6" piece of threaded stock for a lever. I fabricated a peg unto the lever. The shifter lever lasted a couple dozen shifts or so before the threaded stock started to bend.
I then fabricated the bracket in the picture. It has lasted over 600 miles. I'm still searching for something nicer commerically available. If this one holds up I might repaint it and try to make it look halfway respectable.