The trim ring (cork check?), sliding ring, and cap are simple lathe parts. I chuck a 1 inch long rod, turn the two rings and part off. Then I bore the inner diameter of the cap. The expanding mandrel here holds the cap while I turn the outer surface.
You can see here that I am having trouble with the diamond knurl. It is correct on the cap, but shows multiple strikes on the ring. The material for these parts is c642 aluminum bronze.
The wood insert (cherry wood practice blocks here) is easily drilled on my Sherline lathe, using a 4 jaw chuck to hold the square block. Since I don’t have a wood lathe, I also use the Sherline to make the blank round.
Here I am turning with a tool steel bit meant for brass. Both ends of the blank are piloted on brass parts that fit the bore. The brass part at the head end has drive spurs to grip the wood.
And this is the mortised insert, still on the mandrel.
The turned mortise covers an arc of slightly more than 180 degrees on the surface of the insert. So the cap fits very loosely. I would like a better fit and decided to try a milled mortise also.