When you strap a cowboy holster, often times the belt or holster covers the pockets on your trousers, making it inconvenient to get stuff out of your pockets. Milady mentioned this to younger son one day, and over the next week or so, he designed a pouch that fits on her gun belt.
We're concerned with period correctness and he told us that he learned to make these pouches while he was re-enacting the French colonial period of the mid to late 1700s. A simple leather pouch that can be looped on a belt. It's convenient today as it was over 200 years ago. While the early settlers didn't have car keys or cell phones, I'm sure that they had little incidentals they'd like to carry with them during the day.
Just a simple little pouch with a drop-thru closure. It's remarkably secure.
With slots in the back to thread over the gun belt.
This one is big enough for a smart phone, but the craftsman can make it any reasonable size. You'll have to decide how big you like it before you build it, but for carrying some lip balm, a key fob, and maybe a little folding money, this little pouch works great. Blue Eyed Belle uses it pretty regularly when carrying a purse is inconvenient.