I'm toying with the idea too. Problem is I already have far more projects than time to complete them in.
Definitely a back burner sort of thing for me. It would only be for fun, not because I actually need it. I have plenty of low shank machines that will already handle those chores.
I wonder if there would be any sort of a market for modified walking and hopping feet? I know the market would be small these days if it existed at all.
Rodney