I'm sure I'm not the first person to think of something like this, but I don't see any others posts about it, so I'll ask.
If there anybody who might be willing to make an 18650 extender for the JetBeam RRT-01 and/or the TC-R1? I got a TC-R1 the other day, and while it seems to be a great light, it seems that my LiFePO4 batteries don't quite have enough voltage to drive the light to its full potential. I was going to order some LiMn 18350 batteries for it, but if I'm able to use my existing 18650s, that'd be even better. I don't mind an extra 30-35mm on the light (it'd make it easier to hold anyway), get a bit more runtime, and mean that the power draw will be well under the 2C limit for LiCo, even with 2400mAh 18650s (750mAh 16340s don't quite cut it, as based on JB's quoted runtime, it's approaching 3C on those batteries).
Titanium extender would be preferred, give I already have the TC-R1. No special finish is needed other than a polish. There may be more people interested in something like this too, so maybe we could organize some sort of group buy or something.