I have been asked where the tennis balls came from. Well, I made them of course.I got a package of several jacks balls as in playing jacks and took out three of them since tennis balls come in three. (Couldn't find anything to use for a can, durn it.) Then I rubbed white glue on the outside of the ball. I just couldn't get it on the inside. Just kidding. This is so easy I have to add filler to make it worth telling. Then I rolled the gluey balls in dryer lint. Then I rolled them firmly between my hands, yes the glue get on your hands. Now if I had more time and didn't wait until the last minute, I would have rolled it in a certain color of dryer lint. I only had grey around so the balls really look used. Then I tried to be patience and let them dry. I took a pen and drew the markings on. Now you can actually hit the balls with the racket and the balls bounce and the racket stands up to the use. Too much fun.