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 (7/8โ) 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.
The kit instructions say single for salt, multi hole for pepper. We're going to put cayanne pepper in the walnut dispenser a la Chef John (youtube chef).