Making the momentary switch button & copper retaining rings.
I cut three pieces of copper tube, two from 22mm diameter and one from 10mm diameter & filed flat.
The larger pieces are for the front bezel and switch retaining ring, the smaller for the tail switch button.
Cut & filed round a 20mm disc from FR4 board, marked three slot positions, drilled and filed out with small diamond files.
Removed some copper from the outer disc and a 1mm copper wire circle soldered to the back of the cover with slightly less diameter than the Fr4 board to avoid unintentional contact to the flashlight body.
10mm copper tube piece soldered to front and diffusion film cut out to stick underneath.
Chemically antiqued copper facing, diffusion film disc put in place and UV setting glue applied.
Showing 20mm x 2.5mm copper switch retaining ring. 
Using titanium sheet, I marked & cut out a piece, filed round to 8mm diameter and fixed to the centre of the 10mm x 8mm copper tube with JB weld.
And polished.
Acrylic diffuser disc made to sit on top of LEDs and spring fitted.
.
Since the brass bolt is connected directly to the battery negative it seemed logical to fit a spring here and have a momentary on switch connection.
I also made a temporary brass casing from 25mm x 22mm brass tube and inserted the copper retaining rings, though they are not fixed in place.
.
The outer casing, reflector and LED are still temporary but this gives an idea of the finished form.
Test of momentary tail switch button :THUMBS-UP: 
Still waiting on some parts to arrive but we're getting there :-) :THUMBS-UP: