Here in the deep South, many a whitetail scrotum bag covered the gearshift knobs of 4WD Jeeps, Scouts, Dodge Power Wagons, and other pickup trucks. I have seen them used for round ball bags. Most used 20 Mule Team Borox (and old timey washing powder) to preserve and tan them, followed by rubbing in Mink Oil or Neets Foot Oil. Some use a stopper/plug made of antler or wood with the base wrapped with sinew or rawhide (deerhide) lashing. The stopper/plug is similar to a turned powder horn plug slightly larger than the diameter of the round balls used.