Where to get tube extension made?

I was thinking about getting a first light tomahawk for regular use but it requires 2 cr123A batteries for full power. a 17650 is not strong enough, but 2x RCR123 can power it. Problem is that they dont have a lot of energy in them, so I was thinking what if I could get a new body or an extension made allowing me to put in two 17650s or 18650s for a lot of extra time with rechargeables.
Who could manufacture such a thing?
Does this sound like a dumb idea? Yeah the light will end up being longer which is a downside... but i really am thinking about using it for work and 123A batteries can just be so expensive.

I havent bought the tomahawk yet, been sitting on it for the past... 6 months or so. I wish they would upgrade to a Q5 though.

You'd need to check the maximum voltage the Tomahawk can take. 2x CR123A give you 6V, but 2x Li-Ions are 8.4V fully charged.

Im thinking protected though. If i recall someone from the company said it works on RCR123 batteries.

There was a thread in past few months in which some described using a Leef 2x18650 E-head/C-tail tube with the Tomahawk. Some modding and a spacer were necessary.

That sounds interesting, can you provide any more info?