For a neat gift idea why not use a paper with a secret message as the core.
Ball made out of rubber bands.
Easy diy bouncy ball no borax but made with loom bands.
Some people may be interested in using a rubber band around their balls as a diy ball stretcher to stretch your scrotum down.
Colorful rubber bands will make the rubber band ball more exciting and different but the colors will fade with time.
Elastic band balls can be made of any size by folding rubber bands in opposite directions for the center followed by wrapping bands in any direction for the periphery.
When the ball gets too large to fit your rubber bands around cut two bands in half tie the ends together and tie that around the ball.
Some people do this for cosmetic reasons because they prefer the look of a lower hanging scrotum.
This is a particularly great loom bands diy for those of you looking to work without a loom.