It is amazing how one sport, muzzle loading can lead off into working with antler, sewing, leather work, tanning,casting, carving, inletting, scrimshaw, etc. I can think of no other field of hunting that has so many tendrils that reach into so many other things.
I just finished making a "Holtzhammer und Ladestuck" (mallet and loading stick) for an acquaintance that has a German salute gun. The mallet is a usual wooden hammer arrangement, a loading stick is very stout and is used to literally hammer oversize wads down on top the powder. So for an 18 mm bore, the loading stick shank should be about 14 mm, and then a reinforced top to prevent mushrooming while being hit with the mallet. I turned them from pin oak on my lathe.