Its a one off. The 80 Rockwell rollers were from a 70’s pressure fusing copier, none around anymore.
Here‘s a few alternatives, some powered, some hand crank.
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p4432023.m570.l1311&_nkw=grain+mill+grinder&_sacat=0