The VirtuSphere permits a person to walk on the inside surface of a large, hollow ball.

It is kind of like compressing a hollow ball into a solid object.

Each screwed his hollow ball tight shut again, dropped it in his pocket.

A shell is a hollow ball packed with explosive and a fuse.

They are usually made in the form of a hollow ball or tube.

For injury recovery, hollow balls are generally more suitable due to their lighter weight.

Rallying with another tyro, the first thing I noticed was how little the hollow black ball bounced after it hit the floor.

Some would try using hollow balls for the lighter ones.

A hollow ball can hold much more energy in its vibrations.

Just a vacuum, as if the head were a hollow ball with the front panel removed.