The casein is very difficult to find. I got this from a fellow penmaker, and he could only spare about 14 inches. I'm now looking for a source in the UK. If anything comes of it, I'll share.
This casein is very difficult to work. Other casein that I've used was easier. This stuff is soft and brittle. You should have heard me when I cracked the first barrel.
With a wood lathe, a skew would be mandatory, and even then it would take very very light passes.
I used a metal lathe with a very sharp boring bar. Even then, if I took more than .020" per pass at 1400 RPM, I tore out. I went .010" per pass.
Tedious, but worth it.