Make a mixture of glue and water. Slightly blow up one 5 inch round balloon.
Pull out a big bunch of yarn from the yarn ball itself. It is helpful to wrap it around your hand holding onto the end as to avoid tangling of the yarn Dunk the yarn into the glue/water mixture making it all wet. Squeeze it out before wrapping.
Begin wrapping the wet yarn around the small balloon. There is no method here, just wrap it in every which way. Once you have covered up a good majority of the balloon, cut off the yarn and tuck the end under.
Roll the yarn wrapped balloon one more time in the water glue mixture, and then squeeze out any excess. Once all your yarn balls are completely squeezed out, let them dry with the balloons inflated inside overnight.
Next day, the yarn should be stiff and hard. If it is still damp, give it a second day. If it’s dry, you can pop the balloon! Then colorful decorative yarn balls are ready!