When it goes wrong is when you learn. Probably!
It doesn't normally go wrong this many times.
I found a bit more! I wasn't happy with the pickup covers; they didn't quite match anything and I felt the pickups needed to be closer to the strings, so I made some replacement rings. First I made a jig on the CNC. The near bit has four 3mm holes, and I've stuck little bits of 3mm dowel in (actually, I think it was bits of a 3mm bamboo knitting needle). The far bit is less relevant at this stage. Each bit has a reference target.
Next I fix a walnut blank to the near bit of the jig. I use golf grip tape for this - it's fiendishly strong, but peels off easily because it's a crepe paper tape. Lovely stuff.
First the inside gets pocketed:
Then the outside is cut in several passes, then a single full-depth pass taking the last 0.1mm off.
That leaves this, which is cleaned up with the bandsaw and router table, then resawn into two thinner sections.
The cleaned sections go into the top bit of the jig: to be cut to exactly the thickness I want (I know how deep the pocket in the jig is):
Then - sorry, no photo of this bit - the screw relief holes are drilled with a 3mm bit, and you have two rather nice pickup rings.
Strangely, nothing went wrong with this bit...