This is a ball made of an inner tube. Another one of the thousands of uses for bike inner tubes.
Step 1: What Do You Need?
Here is what you need:
1 Bike Inner Tube
Sharp Scissors or Knife (Scissors Make It A Lot Easier)
Step 2: Making the Inner Tube Rings and the Yarn Ball
Ok, this is simple. Make a yarn ball the approximate diameter of the inner tube. Then cut the inner tube into about a quarter of an inch wide rings. Cut between 30-40 depending on how big you want it.
Step 3: Actually Making the Ball
I would start by putting one band around the loose string so it doesn't get in the way. Then keep on stretching the bands around the yarn ball at a point(see pictures). Once you get about five like that, take one band around the middle and keep on alternating like this until no yarn is showing, or its to your desired thickness. Or, you could put the bands around randomly. The alternating design keeps it from getting too lumpy.
Step 4: Finishing Up
All you do is take 4 half inch wide or larger pieces and wrap them on. That way it is smooth, and it will roll better. Or you can leave it how it is for a rough and more grippy surface. It doesn't bounce well, but it rolls for a while. It is kind of hard and dense, so don't peg it at people. It will hurt.