The Koosh is a toy ball made of rubber filaments (strings) attached to a soft rubber core. Engineer Scott Stillinger invented the original concept in 1987 by tying rubber bands together to make a small, easy-to-catch ball for his own young children. The toy caught on, earning the name "koosh" from the sound it makes when caught. Millions have been sold since then, when Stillinger started the company, OddzOn Products Inc. just for Koosh. Though you can purchase several different sizes, colours and styles of Koosh balls at many toy and department stores, you can also make your own.
Wrap each of the standard rubber bands once around your square of mat board, side by side. Do not overlap any of the rubber bands.
Carefully remove the mat board with one hand, using your other hand to keep the rubber bands as even as possible.
Slide your thick rubber band around the centre of your mass of standard rubber bands. Wrap the rubber band around and around until it is tight.
Cut the loops of the tops and bottoms of your standard rubber bands. Leave a few loops intact so you can use the Koosh ball as a slingshot. This is how commercial Koosh balls are manufactured and sold.