A connector between 2 parts of the broom. Thread on one side, a snug fit socket on the other. The onshape model is parametric and must be customized for your broom.
The attached STL is just what works for mine.

Print with 100% infill, 3 M3 countersunk bolts are required to provide reasonable strength to the part. You may need to get them hot with a blowtorch or a heatgun to fasten them smoothly.

Onshape link: https://cad.onshape.com/documents/d625f1be1bbcb84854faefa5/w/83101a841b2086d58e5236ea/e/98a33a30b8c858029ccf070b?renderMode=0&uiState=633ffedf73d49c0e7968ae7b