Jacob Dunnack, 8, always has a ball when he swings a bat. He uses a JD Batball, a plastic bat that stores baseballs inside its hollow center. Jacob invented it two years ago. He got the idea during a trip to his grandmother’s house. Jacob brought his bat but forgot to pack his baseballs. "My grandmother had to make paper balls!" says Jacob, who lives in Willimantic, Connecticut. He helped an engineer design the JD Batball, which is sold at Toys "R" Us stores nationwide.