Lawrie, there are not too many sheaths makers, whether leather or kydex, who possess let alone own various CPK patterns. I know that Grog personally owns quite a few CPKs but he didn't embark on buying CPKs with the intention of commercializing his sideline hobby, i.e, leather sheath making. I personally trust Grog fully to send him the patterns which he does not own and have done so a few times in the past.
I know that Gus also has had a relationship with Bud who makes leather sheaths on a much larger scales as compared to Grog. I think some of Bud's sheaths made for other patterns also fit certain CPKs but I do to know for certain. Gus will be a much higher authority to opine on what he sends out to Bud, what CPKs Bud already owns and what other Bud made sheaths also fit CPK patterns.
Lastly, I know that Justin, Ivan and Jake have used Sagewood Gear but I don't know as to whom sent Brian at SWG the CPK patterns, perhaps it was Justin? Oh, High Standard who is also an occasional poster on here dabbles in leather making and I have seen some great work from him too (sorry, I am not familiar with his name on a first name basis).
Hope that this helps
P.S. I am sorry as I forgot about Rick Lowe, RLO Sheaths. He has made some EDC & FK leather + leather/kydex combo sheaths in the past.