Last fall I finally got around to purchasing an SRK clone with 3 LEDs but of course it has no solid shelf or even screw in pill, just a lip that barely a mm of the mcpcb rests on. Having fried LEDs on even lower powered lights I figured I’d want to add at least a pill of some kind so I set out to make one out of copper. It’s not solid, just a 1.8mm plate that conducts the heat to even thinner copper sheet fitted to the tube ID. A second thin sheet strip gets added to increase the conductivity from one to the other. I started by cutting the two strips of thin sheet with shears with the width slightly less than the length of the cavity and truing one edge to some extent. Then I cut the larger one to length( pi X D) and after annealing and fitting it brazed it together. 
Getting the seam edges even is tricky but manageable if you’re sufficiently endowed with OCD. Once it was brazed and cleaned it slipped right in. 
Taking it out, annealing, and rolling it in place helps relax it to fit well without any spring in the shape. At that point I scribe the ring onto the thicker sheet and rough cut it with the shears.
I also cut and fitted the narrower strip as well and annealed both to shape them(one to get it flat and the other to get it round so it wouldn’t tweak the outer piece out of shape. Then I applied flux and cut several short pieces of brazing wire to place them around the inside perimeter at the joint and fired it with the Mapp torch. 
After cleaning the flux residue I use the shears to trim the bulk of the excess and began the lapping process. In this case I did a fair job of getting it flat so it didn’t take too much sanding and filing to bring the high spots down to the low areas. I’ll still need to grind/file the remaining excess for it to slip in the rest of the way and will also need to drill the wire holes for led current and control switch but I’m happy with the progress so far. My biggest doubt was whether the ring would stay sufficiently round after the second braze which joined it to the flat. 
It’s not a press fit but from the second pic it can be seen to be snug enough not to fall through on its own and that should be enough improvement for my needs. A tighter fit could be had by layering the outside with solder and wiping off the excess but I won’t be doing that.
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Here it is fitted 
The sinkpads and emitters I’ll use, oldies but goodies. The bag was still sealed. 
After refloweing the emitters I used the stock reflector as a jig and glued the stars together her with JB. After that cured I made buss bars of copper and reflowed them to the pre tinned star pads. I also located and drilled the holes for the reflector screw, awg18 wires, and momentary switch connection. 
Here it is with the drive wires in place. 
And here with the temp sensor glued into the sink. 
Hopefully next time home will see it assembled. All that space in the sink will come in handy. I do need to pick up a longer reflector screw as the original isn’t long enough to go through the added copper.
