Here"s one I built awhile back. I sold it last summer, but that just gives me an excuse to build another ( like I need I reason to start a new project )
I took a scull head shifter knob you could get at a auto parts store, then I drilled and tapped Holes for the spikes. The base part of the shifter is Sturmy Archer, I cut off the lever and handle they had on it, then I rolled some round aluminum rod, tapped one end for the scull head and molded the other end onto the base.
Thanks, Al. When you're 6'4" you need a long seat post. This bike is still really small for me. I'm adding a stem that will increase my reach and some bull horn bars too.