There are eight walnut discs of unequal sizes which fit into the beech dish. The sizes are calculated carefully
But first, a prototype is created in plywood. The dish is exactly 200.0 mm in diameter and the discs are a tight fit
Each disc is made simply by mounting it on a screw chuck, with a plywood backing disc, and cutting it to the correct diameter (with a round skew)
The walnut discs are from 40.0mm to 83.8mm, so slightly different techniques are needed to make each one. Start by cutting the blank roughly circular and making a spigot
Reverse chuck, make a flat face and carefully cut to the correct diameter (checking with the vernier callipers)
As each disc is completed, check it by insertion into the plywood prototype