Step 1: Fill the balloon with water.
Step 2: Freezing the balloon
(freeze for at least 5 or 6 hours.)
when you go to freeze the balloon, make sure NOT to underfreeze. if you do, your ball of ice may crack and gush all over your freezer.
Step 3: Remove from freezer
A crack will usually form somewhere on the ball of ice, and water will leak from the center. If it doesn't leak properly try using some hot water to make a hole.
remove from freezer, and enjoy.