Hello!
I hate to say it, but 26650 just isn't that popular quite yet (at least not like 18650). There are a few mechanical mods for that size, and tons of home built box mods that take dual 26650 and longevity with two
batteries is amazing! I would start looking on E-bay or Facebook for folks who make them.
I would highly recommend a regulated box
mod. I was one (not to long ago) who swore I'd never go to box mods, but since then, I've purchased 9 different boxs! Now, My tube mods collect dust.
Good luck!!!!