On second thoughts Sironae, I think those really large wooden beads would be better, only I just don't have the time right at the moment.

I only got as far as looking for them:

https://www.amazon.co.uk/gp/product/...=AA765L7AOGAM0

This is what I might get if I EVER get around to trying something like you have with the egg

There are bigger ones - up to 80mm diameter, but they seem to get unreasonably and disproportionately more expensive after 50mm