Stabilize ball by placing on top of a short cup. Glue corks on, placing them as closely together as possible.
To fill in any gaps and prevent the styrofoam from showing, you can cut down a cork to create a point that will allow it to fit tightly in-between corks.
Cutting down the end of the cork allows it fit between the other corks and create a more finished look.
Continue until ball is covered.