I made some changes to an earlier design as suggested by tk59, JC, Bao (many thanks to you!).
Length and width of the tapers on both sides will vary from a handle to a handle. I also plan to introduce a similar modification to an octagonal shape handle.
Some of the horn I have (picture at the top) has these amazing brown lines, looking more like wood. That was a very pleasant discovery.
Opinions and criticism are welcome.