I'll agree with the above sentiments - sometimes a guy can order a large soda, then find themselves drinking through a firehose. Nobody wants to play a game where they take orders and but then have excessive and/or inconsistent lead times, or worse, have portions of the year where you're not taking new orders... People are used to online ordering where they can get what they want, when they want it. So if it's a one man shop, he has to design his go-to-market strategy accordingly - think small & sustainable. Work with a local CAS/SASS club, heck, a guy can drum up a lot of sales by asking guys to "test" your rigs and give you feedback on designs.
Developing a good website, then working with different gunshops and having them place a stack of cards on their counter can be productive. Offer them a 5-10% commission, and/or a 10% discount to folks referred through there. Or offer them some inventory as examples. You have the option of wholesaling to the retailer, or consigning - but the inventory HAS to move, either way, else the retailer is looking at wasted inventory cost, or the consignee is stuck with floor/wall space which isn't yielding revenue.
Is he unwilling to work any kydex? A lot of holster makers are using kydex liners even in leather rigs, and it's not difficult to learn to work, so it's typically a worthwhile investment, considering it'll open up a much larger market, AND diversify his portfolio. I would go as far to say there are more small companies kicking ass and taking names doing ONLY kydex than there are doing ONLY leather. I bought a garage sale toaster oven and built a set of presses for FAR, FAR, FAR less than I have invested in my leatherworking tools. Heck, my "good set" of leathercarving tools cost more than what I have invested in my kydex gear, let alone when you start talking about sewing machines!