I rolled it across the floor for Gambit to see and hopefully attack and he just sniffed, looked at me as if he was saying "And you expect me to do what exactly??...." and sauntered away to go stretch out on the bed. Lazy cat!
I put several layers of stuffing around the outside of the ball and then inserted the jingle ball. Added more stuffing to cover and then sewed it shut. Looking at it, I'd say it would also make a pretty neat baby toy as well since there are no sharp pieces to poke out anywhere and it's soft.
The pattern can be found here.