If you're going to make cartridges, I would suggest a belt, and depending on how many rounds you want to carry, a leather cartridge box. I believe the regulation box for revolver held 12 rounds, was small and worn on the belt. For more ammo a carbine cartridge box worn on the belt isn't too big and would probably hold 30-40(?) cartridges. A tooth brush, rag, maybe a capper, knife with a screw driver blade, and a snuff tin for grease. You'll probably already be carrying some water, possibly a rod and bore brush if it's an all day outing.
The leather goods can be had from S&S Firearms
www.ssfirearms.com