I tried to make one years ago, but never had any luck getting it right. Bought a Bohnning (no need to get the "Pro"--a lot of extra money and basically you just get a drip tray that isn't even needed), have since moved up to an Arrow Specialties. With some stuff you'll spend more money and still not have as good as you would have if you just bought it.

That being said, I think you can buy just the chuck from Bohnning, but I have no idea what it costs.

Chad