There is a company that sold a Rubber corrugated hose, just like the old rad hoses you found on vehicles in the 50’s.
Nice thing with a soft rubber vs plastic is, it doesn’t give you that “tinny sound”.
You will also see some tubes have a heavy rubber band around them to reduce that also.
I may try to find an inner tube to fully wrap around the tube I have.
I have one of those large tubes, and then the corrugated hose mounted to it.
I was considering buying the Abe and Sons tube and seeing if i could cut out that sound chamber and modify in between the rubber hose.
As some one said, it can get expensive.
I think most real avid elk callers have dozens of different manufactures diaphragms, hand held cow call and tubes sitting around, trying to find what works best for them.
Back when I started, there weren’t many folks that you could learn from.
Larry D Jones, Carleton we’re probably some of the first to get deep into it and showing different techniques on calling sounds and ways to hunt elk, imo.
So very few hunters out there in the field that were good.
Today there are so many folks that are damn good at it.
And there will be plenty of different views and opinions to draw from.