Back in the early 80's, I ordered these tools and many others from McMillen Tool Company in Sunrise Beach, Missouri.  They established business in Kansas City back in 1898 and produce some of the finest leather tools in the business.  As far as I know, they are still in business.  Their prices are quite high, but so is the quality.  The delivery time on most items is long.  You can only reach them by phone or mail.  This is the last phone number I have (573)374-7880.  Best thing to do is call and ask if they still put out a catalog.  The last one I have is #77, which I believe was around 2012.  I also have an awesome original McMillen catalog from around 1910.   Hope this will help.

On the castboolits forum there is a member , DougGuy, that can take your cylinder throats to the size you want.  Although I have not had any work performed by him, he would be my first choice for any cylinder that work I needed.  I don’t recall ever hearing anything negative about his work.

Dave T's comment on derringers reminded me of a belt buckle I had.  Had a derringer that clipped on the buckle and was spring loaded.  Pushing your stomach out caused the gun to flip open and fire a cap.

That's a beautiful rig and I think Marshal has pointed you in the right direction.

Tree forts another treasured memory  I built several.
One I recall, in an old tall Banyon tree about 50 or so feet from Biscayne Bay (Miami) just north of the Rickenbacker Causeway I swear it was 30' up, It had 3 levels of decks.
We could see way out across the bay and in to Seaquarium no other trees anywhere near that height.
Developers cut and bulldozed it in 1960 to build the Brickel building. There was also a coral rock cave nearby we played pirates in, they also razed.
 In October of 2016 a portion of the building under re-model collapsed.