Poke a hole into the tennis ball with a hammer and a nail. Repeat for the 2nd tennis ball.
Step 3: Insert Here
Before you put the string in tie a knot at both ends of the string. To get the string in push it in with a flat head screwdriver. Repeat for the 2nd tennis ball.
Step 4: Enjoy
Enjoy your new toy!
Step 5: How to Use Them
To use them simply hold the center of the string and lift one of the tennis balls allowing it to bounce off the other. When it bounces off, lift/jerk the string to separate the tennis balls and give it lift. Once you've gotten good at it move your hand up and down to make a 180 degree.