My vision for a grain mill that also cracks nuts didn't exactly work out the first time. The major flaw was that putting a round nut between a driven and idle roller caused the second roller to spin backwards. What I needed was a roller with lobes on it that would grip the nuts and force them into the other wheel instead of just slipping.
I had two options for making this; 1. I could start with round material and mill a bunch of slots in the sides, or 2. I could start with a rectangular piece, drill a bunch of holes in it, then cut it out with the band saw and turn it on the lathe. I chose the second option because it sounded like more fun.