Old Tennis Balls
Blue Bins & Chutes
Turn your old balls into new sports tracks!
Teloon Tennis Ball Recycling
Freecycle / Give Away
Some dog shelters may appreciate old tennis balls though most will be overwhelmed with supply.
Alternatively, check out Project Yellowship.
Tips & Suggestions
Your local dog park may welcome tennis balls for the dogs to play with.
Don't know where there are dog parks? Many are listed online.