Single piece, simple ball turner.

[Toolmaker51]

(abbreviated) A memory damaged by age is a terrible thing. i remembered as soon as I finished it that I had previously considered two other methods for making ball ends. Why wasn't it before I made this ball turner that I remembered these almost zero work options?

Well you mentioned considering a ball turner for decades. Both other solutions are feasible, perhaps turning beats milling by eliminating 1 axis?
Any how, it seems memory is subject to more than just age...Few of us can create items quicker than conceive them.