I don't know about making others but I am certainly interested in the challenge of redesigning the setup so that it will be more durable than the original. Of course this also means maintaining the original metal hub because I do not have the machinery to manufacture an alternative. That is where the challenge comes into it.
The approach you outlined is something I have been pondering as I think there needs to be a greater key between the hub and the plastic ring gear. I was thinking a basic spline setup (grooves cut with an angle grinder is the simple option but lacks the finesse I am looking for).
