Retractible Cord Or RubberBand Battery

thingiverse

Create a rubber band-powered spool with adjustable length posts, suitable for various applications. Shorten the posts if not required; use as a retractable key or lighter leash, combined with a Bic lighter holster. Alternatively, employ it as a powered wheel by omitting the string and wedging the rubber band between shells and spool. Attach the wheel to the spool's posts for free rotation, ideal for pull toys. Print all three parts with support for the spool; coil string around it, pass through inner and outer shells, then thread a rubber band via center and side holes of shells. Secure with a filament piece looped around the rubber band to keep it in place. Resize as needed for different power requirements or string length.