Now that I’ve used mine so much, I wish Jetbeam would make a 18650 body for it…
I thought about modifying mine with a lathe to add so length in the narrowest part of the original tube but I’m afraid of ruining it…
Niteye eye15… :question:
Well it’s discountinued, plus I’d prefer to keep the RRT-01 and just have triple the runtime…
Thanks anyway !
But if you could find one I’m sure it’ll screw right on to the rrt-01 head 
unless you mean the new rrt-01 
these tubes are made of UnObtanium:
yes, Eye15 legos with Original RRT-01 and Eye10, and TCR-1
X3 has the New Phat Head version, so needs to manufacture a new tube
or a custom adapter for the New Phat Head to fit something like the DSpeck UBH
http://www3.sympatico.ca/d.speck/UBH-Infopage/
For anyone who wants to run an 18650 with your original RRT-01: a Crelant 7G3CS battery tube fits nicely onto the original RRT-01’s head. Gives the RRT-01 more runtime with a lockout clicky. Overall length is roughly 120mm, IIRC . Anodize color will be off, but I use my lights for more than photo-ops.
Cheaper and much less time consuming than taking to the lathe and CNC.
The light lends itself to much improvistion. The screw in lanyard makes adding machined or 3D printed attachments easy as well. On a 3D printer, I made a twist off RRT01 lanyard cap for father-in -law that holds pills and hearing aid batteries 
I’d thought about a adapter that would thread to the head and to the tube, like sunwayman did with the V11R and V10R.
Well if I could buy a spare 18350 tube, I would try to mod it but I don’t want to ruin the light at all
The new RRT-01 tube is built very thin, not much beef for modding is my impression.
Incidentally, the threads in the old RRT-01 are compatible with the threads in the Manker E14 / Astrolux S41.
This means you can take an 18650 tube from those lights and lego it onto your old version RRT-01 head to get instant 18650 support.
There also tailcaps available for that thread pitch without without switches on them. So if you want a flat back with no switch it’s possible to do. I just tried it with parts on hand and it worked.
While the threads on those lights are the same as the threads on the RRT-01 head, it should be noted that there are more threads on the Astrolux/Manker tubes. If you want it to be watertight and cover the o-ring on the body tube you may need to shorten the threads slightly by sawing or filing off the top of the battery tube.
The old RRT01 also legos with a Convoy S2 tube, IIRC. But it requires sanding down the tube threads to make it short enough for a good fit. Or dealing with exposed threads and no waterproofing.
Now let’s find where to buy and old RRT01
and here is a replacement reflector for the Original RRT-01
following info courtesy of Coppet:
a replacement lens that also fits 2019 RRT-01
and a black clip option that also fits 2019 RRT-01
Lol 138 bucks for an outdated product
Sounds better when you convert to USD. Don’t you feel sorry for us Aussies 
Oh, those are AUD ? sorry I didn’t see it 
ANyway, that’s still more or less the price for the 2019 version 
But most of us do prefer the old model.
I like the looks of the new model, the old model looks somewhat boring (except the Ti model, but then: the new model in Ti would look even better )
I find the new model to bulky for EDC and almost double the weight.