I am trying to make a free floating square inside a 1/2 inch ball as an art project. So I am dreaming up ways to turn a square piece into a round ball. And I think this will work. I will start with 1/2 inch sq cubes and cut the free floating squares inside them then I will form the ball with the hand ground form tool that I made. It will take two homemade form tools to complete the ball. To make the part shown with the legs I used a cube held in a 1/2 inch sq 5c collet with a collet stop in it. Then I made a 1/2 radius form tool about 5/16 wide to form ball . Then I turned cube in collet and formed it the other way. When I make the part with the sq inside I will first hold cube in collet then form 1/2 radius in center of part ,then hold on the 1/2 ball to use other homemade radius tool to finish both ends of ball . I will post pic when I get it done.
Oops I meant a 1/4 inch radius to form the 1/2 inch ball.
I have made a lot of radius form tools and have found that if I give the tool enough top back rake I don't have too much chatter. But in this case I may use both my homemade ball turner and a form tool.