Big and beautiful. Get a pair of those together and I bet it'll do a pound of grain every 1.75 revolutions of the rollers. At that rate, it will never wear out.
j/k about the revolutions. I have no idea really, but I bet it'll throw down some milled grain fast!
Man, I wish I had a mini-lathe and the space to set one up. That is too cool! What metal did you end up using? Plain steel?