Froggy wrote:'Something simple'?
Not in my world. That's fantastic. I live in the French countryside surrounded by Chestnut trees and I don't think I've ever seen a chestnut tree with burr. I'll look more closely tomorrow.
I counted 10 going in and 10 coming out just keep your fingers behind the tool rest and don't move the tool rest while it is still turning OK OK so I did forget the last bit but but luckily only a piece of the bark came off so no damage to the main bowl.
These are not as difficult as people think as long as common sense is used if it does not feel right don't do it if you do take it easy and once the outside has been turned and finished add something around the piece like a heavy duty tape or heavy duty cling film not the flimsy stuff you buy for the house.
work from the rim in steps maybe 1" at a time and finish before moving down to the next inch and never go back to the rim again once hollowed that way you don't put unnecessary pressure on the bowl where it may break