This project is for a quick massager that you can use at home or even on court if a sudden injury occurs.
What you need
2 Tennis Balls
Large sports sock
Take the sports sock and place two tennis balls into the sock and tie the top of the sock up with either a elastic band/hair band or a knot.
You can also use squash balls for this one too.
To use have someone rub it over your back, legs etc or lay on top of it on the floor and roll yourself back and forth.