I've got some follow along video series on holster making, from making a pattern to buffing the final finish. It covers the tools, leather, dyes, finish, edge burnishing techniques, stitching and other stuff.
There's lotsa ways to get the same results, these are just how I do it.
https://www.youtube.com/channel/UCOM3hbruUKHov9kquIxXKlA/videos
Generally I use 9-10 ounce for holsters, 6-7 ounce for pocket holsters.