Hi Rob,
I know nothing about 26650 batteries but have you ever considered a 26650 Reo.
At first looking at the dimensions the battery is 8mm bigger diameter but may be feesable to fit by only increasing the Reo by 3mm (width and depth) although with very thin walls.
Only a passing thought but I would imagine you have plenty to take up your time currently with the sub - ohm kits so please let this thread die if you wish.
I know nothing about 26650 batteries but have you ever considered a 26650 Reo.
At first looking at the dimensions the battery is 8mm bigger diameter but may be feesable to fit by only increasing the Reo by 3mm (width and depth) although with very thin walls.
Only a passing thought but I would imagine you have plenty to take up your time currently with the sub - ohm kits so please let this thread die if you wish.