Yes, quite an interesting method, thank you for the link. The first set of drives must need accurate placement of the blank so not sure of that.I have made a wooden drive which sits in the chuck and have an egg cup chuck thingy which sits in a multi star revolving centre.
In the seminar at Stone I saw Max Brosi turn spheres freely using geometry and a good eye. I have tried it since and found it OK as it is not a size specific system. I also saw Rod Page using a home made jig to turn spheres.
ATB John