I have this hunk of locust (close relative of mulberry and Osage orange), so I figured I'd use it for a first shot. It's rock hard, and takes a lovely polish.
First I thought something simple, with the draught hole and mortise in-line:

If that goes well, I was thinking something with a more bent stem, and kind of a V-shaped chamber.

I hope to have some progress pictures to share soon!
Edit: made the images smaller and clickable, instead of ginormous.