You could make a mould for the S2+ and S6’s for FET and Q.lite drivers to pot the driver areas. Leave enough gap to isolate the aluminum heatsink electrically and short enough to put a heat isolating pad between it and the emitter shelf and I bet it would be a winner.
I’m new to flashlights, so FET is all I understood. But like I said, send me a file, or even a simple drawing, and I can make it happen.
+1
You’d be better off making a plaster cast. I don’t think it’s worth making a 3D model for. Just lube up a driver and pill cavity and put in silicone. Let it cure, pull it out and clean it up with a razor blade and cut wire channels, then press it into wet plaster with about 1/16” of the emitter shelf side exposed (to shorten it’s overall height for room for heat shielding material) to make your mould, remove the silicone when the plaster is cured and pour away.
I can send a simple drawing.
This is the first thing I ever made from aluminum. It is 5.33” long. I made a 3D print (left) then packed sand around it, pulled it out, and poured aluminum. Not bad for a first try 
Aluminum is a great conductor of heat, but copper is a little better I think. I can probably melt and cast copper too, but I would need to charge for buying the supplies.
Alright, this is what Ronin42 asked for:
And DB Customer asked for this:
Anything else guys? So far these little pieces are barely worth firing the kiln for. Let’s get a few more.
I read, I think it was in a Materials Engineering journal, that forged aluminum wheels are better than cast aluminum wheels, but I think wheels are still mostly cast and they work well.
It would be interesting to cast the outside of a flashlight to get smooth curves without an NC lathe, but I don’t have access to a manual lathe to finish threaded and sliding surfaces.
From my experience, I agree Fritz. Articles are written about how forged is better, but in a practical sense, it’s not such a big deal. Especially for something non-load bearing, like flashlights.
For finishing, I could leave a small shaft stick out one end so you could spin it in a drill and squeeze it with sand paper.
How complex can you cast? How about a Nitecore EC4? It’s body is one piece cast aluminum. I don’t have one myself so I can’t provide measurements. :~
You’re asking him to die-cast you a Nitecore EC4 body so you can make your own clone? 
It’s a good question. Yes, complex shapes are possible, but not with sand casting. It would have to be done with investment casting. So I can print a whole flashlight in PLA plastic, attach a glue-stick or two for runners, then bury it in plaster investment. When that cures, you put it in an incinerator and tend to it all day long. At the end of the day, you remove the hollowed out plaster mold, pour in liquid aluminum, and let it cool. Then you break it open and have a flashlight host. So yea I can do it, but setting aside a whole day for the finicky process would cost more than buying the host from a mass production process.
Here’s a picture of my second aluminum creation. Not bad for a first try at a new skill!
So that is a air compressor fitting you see. And it works without leaking
Found this on youtube, How To Turn Styrofoam, Into Solid Aluminum
Yea, Styrofoam will vaporize, so I hear it works cool. But I don’t have Styrofoam or a way to form it.
There was a thread of 3D printed flashlights in silver. Really beautiful. I can’t think of how to find it quickly.
I’ve played with lost foam casting, you can just pack the form in sand and pour. A mill to cut the foam could be made like a little 3d printed with the extrusion head replaced with a dremel.
I was just wondering. I figured the effort would be too much to be worth it.
I’ve got an EC4, it’s pretty complex, amazed they could do it this way. Neat light, quite different from the run of the mill lights we see all the time.
Is your EC4 still stock? 