it makes sense to get a long skinny shaft since I have this mounting thing, but since i'm doing this right now, i'm thinking of other solutions.
I could glue or otherwise affix a dowel to something flat, possibly. I could buy a dowel from a hardware store. I could use a pencil. I could use a metal rod: this seems it would work better. Like, a coathanger may work. I could possibly use the bolts to affix a bent coathanger to the bracket, and lash the shaft to the bolts to keep it in place. Winding a cable might tighten the lashing. This seems unlikely to work given how my hands spasm and shake, but it's an idea and may work.
