Just finished this set. Black walnut and maple blanks. The hardware is from Lee Valley .
The insert gets glued in the blank with the metal cap screwing on. I wasn't super happy with the kit because it's expensive and needs odd-sized holes. I bored undersized (7/8“) and expanded with a square end scraper, but the taper on the tubes makes it difficult to get a snug, consistent fit. Had to use some blue tape to shim the gap.
That's wild I'd never heard of anyone doing that!
What can I say? We do like our pepper!