Inflate a long balloon, leaving a few inches uninflated at the end
Tie the balloon securely
Twist the balloon about one-third of the way from the tied end to form the handle
Twist again a short distance above the handle to form the guard
Fold the remaining long section in half to create the blade shape
Twist the folded section near the guard to lock the shape in place
Straighten the blade section so it resembles a sword
Adjust the twists gently to keep the sword shape stable