In this Instructable I will teach you how to make a tennis ball compartment. For this all you will need is a tennis ball and a serated and pointy knife.
Step 1: Cutting the Ball
All you do is find the longest stretch of straight white line on the ball and saw along the line after a while stab your knife through the white line and saw down the straight line.
Step 2: How to Open
To open it you have to put you thumb and your index finger either side of where you cut and squeeze as I am doing in the photo.