I make them myself on a wood lathe. Before the lathe, I did it on a drill press. Got a piece of round brass stock, drilled a blind hole and tapped it for 3/8 coarse thread and then screwed it to 3/8 headless bold and turned the stock into a jag using a coarse file to rough shape it and then fine sand paper to final size and polish. removed the bolt and screwed in a piece of 3/8 inch wood. I have seen various ways to make other cleaning "utensils" a round piece. One of the nicer ones I saw, was a large Phillips screw driver with a round shaft. The guy heated the end to remove the temper and threaded about a 1/2 inch for a cleaning jag.