After the very obvious penny had dropped, I managed to join the two halves to get a ball. This one works about about 30 cms around so quite a big bigger than the first ball.
Bear is now spoiled for choice over which one to play with. We tend to have some upstairs and some downstairs so he has one wherever he goes.
I think it's time to make something for Finley, he could be feeling left out after all the attention Bear has been getting.