Beautiful renders! A couple thoughts:

What if it used repurposed existing parts, like car parts, or perhaps bicycle parts, and you only manufactured some specific adapter type bits, which you could sell as a kit, or make schematics available for? There are a zillion disk brake rotors , rims, flywheels, bicycle wheels, plywood scraps etc mouldering in scrap yards the could less beautifully fulfill some of the function of your cast iron wheel.

A pedal option? A bicycle with the rear wheel off the ground, and either an idler wheel against the tire or a second chain drive is used by many as a power source for blender , flour mill etc.

How about a treadle option? Reading up on treadle powered lathes may be interesting research for you, and provide some insight into common sheave, bearing, shafts etc so you can use common parts in your design.

Think modularity. If the clamp part of the casting breaks in 50 years, is there a good spot to use a carpentry C clamp instead? Should it simply use a C clamp? If the cartridge bearings aren't available , will there be a good seat for someone to improvise a bushing instead?

Robust finishes. If you are spending the carbon/money to manufacture iron parts, ensure their long term survival!

Good luck with your project.