I find it interesting that there is such a convergence towards hubless wheels, which I think are challenging regardless of number. There are a handful that have

I find it interesting that there is such a convergence towards hubless wheels, which I think are challenging regardless of number. There are a handful that have hubs but if the passenger is on top they drift into unicycle territory, which feels like a different category -- and if the passenger is inside, then the whole vehicle is perhaps large enough that it's further out of reach for an independent hobbyist project?