There is an antique sandwich case with a flask being offered on E-bay right now. It is one of the nicest ones I have ever seen.. but the opening bid represents it's condition at a whopping $399.00!
I am not sure why there is not at least one saddle repair specialist that does not make modern versions of something like this. It seems simple enough and even at half the price, it would be profitable. Even though I do not hunt, I would consider having one just because I love to trail ride!