I designed this because we needed a slightly longer handle on a microfiber duster.

Printing is straightforward. The one pictured was done in PETG with a 0.3mm layer height, no supports.

To use, thread the locking ring onto the grip all the way, thread the grip into the duster/mop/broom end, align the grip so that it feels comfortable, then secure the locking ring against the duster/mop/broom end to hold the grip in place.

Feel free to modify or remix as needed.