I know there is a market for them, and buyers are fussier about the mag pouch fit and function than the holster.
I have friends that are leather workers, the reason I haven't ventured into it, and we are on the FNRA committee together. I attended my first SASS match and introduced them to the gang. At the last gunshow they were overwhelmed with SASS members, which lead to a lot of other attention, over leather needs. The number one thing I heard was mag pouches that meet Wild Bunch rules, and that lead to many other areas of mag pouches.
With all the commercial options, and the catalogs and net resources, I never realized how much demand there would be for local custom work.