That would be a perfect project for someone with a 3-D printer!
Mark
When I was in a similar need I made my own! Full story here It might worth to give it a try.
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If using thin mild steed rather than aluminum, it would be stronger and easier to afffix (weld or braze) the hub part.
If you were planning to bolt it on, aluminum would work OK. It all depends on what tools and or welding
equipment you may have. A TIG welder(GTAW) would be a great tool to use if you made an aluminum one but
not everyone has one, including me. Good luck.