Use this procedure to change the radius of a circular mass element using grips. Circular mass elements include Cones, Cylinders, Domes, Doric Columns, Spheres, and Revolutions.
You can also change the mass element radius on the Properties palette.
Editing a Dome mass element with its Radius grip
You can select any one of the radius grips on the same circle to change the size.
The mass element becomes larger or smaller depending on the direction you move the grip.