Making the mechanical rotary tail switch.
Copper washer.
Using a scrap piece of 0.3mm copper sheet I drilled a 4mm hole and filed the outer edge into rough shape with the file before switching to the finer stone then a quick polish.
Sprung brass switch contacts & enclosure supports.
I used an old brass Zippo flint stopper to make a switch contact.
Filed the brass rod down a little, sanded and soldered to a silver coated spring from an old clicky switch.
Cut two contact enclosures from 3mm x 0.5mm brass tube and filed down to 5mm length then neatened up with the fine stone & sandpaper.
Two sprung pieces, only one is for making the circuit, the other is made to balance the switch disc, is non conductive and also showing a 5mm x 4mm brass tube to be filed down to 3.8mm length for the central pillar support.
Some switch pieces.
Rotary switch contact boards.
Using the FR4 copper board again, I drilled, cut & filed an 18.92mm diameter disc with a 4mm centre hole.
Using the first as a template I sanded down the second using an M4 brass bolt & nut holding them together.
Now we have two equal contact discs 
I marked six points on one as well as I could freehand.
Further marked, kapton tape applied to both sides then I cut out the tape roughly where marked with a scalpel blade.
I used ferric chloride to dissolve away the copper that was not covered with the tape, this takes a few minutes.
Pieces removed from the acid bath, cleaned and tape removed from boards to leave copper contact points hopefully where I want them. 
A little more tidying up and ready for test assembly. It is not OSH Park quality but it is all hand made 
Order of how the parts go together. 
The brass contact enclosures will be soldered in place to the disc later.
The steel washer is temporary to hold the contacts in place and will not be used when everything is soldered.
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