Ken,
The first one in the second row, walnut and box elder, is what I had
in mind. Picture that one upside down, the smaller diameter ball would
be where the 3/8" tenon fit in so it wouldn't be hollowed, then the top
just like yours. Any advice on knowing how far to turn during the
first process so I don't have the SS Niles Stopper tenon poking
through? Now, what else do you think I'd be using!?! : )

I've never even tried inside-out turning yet, so it will be a learning
experience.

Thanks,
Ruth
www.torne-lignum.com