I saw a jig someone made for turning spheres.
It is a banjo type jig that holds a tool and bolts to the bed. The idea is that the tool is attached to the rest and it only swivels around in circles (ie, a sphere). Once roughed out, the jig could make spheres pretty quick. I just can't find the link and don't remember how the jig was made. I do remember he had a cup chuck with a hose clamp like what is used to do eggs. He used it to clean up the ends.
I will keep looking.. seems like i remember he made the spheres for juggling balls.