Hope you don't mind me sharing this here Craig, it's part 2 of the BB-8 build that someone is doing on Youtube. I posted part 1 earlier. He's doing it slightly differently from yourself (due to him building it before the SW convention appearance of the physical droid) but it's fascinating and enjoyable watching nonetheless and thought it may be of general interest.



The 12-minute mark is where it's self balancing on both axes.