Slim ecigs should only use things 2.5 to 3 ohms and the choices for most
tanks are dual coil (WAY too low ohms), Boge 2.0 (somewhat too) and Boge 3 ohm (will not be as warm as your Volt cartos)
Optimal I think would be a tank that fits the 2.6ohm steel Kanger horizontal coil cartos are the same ohms as Volt/Bloog cartos. But they may be the same diameter as Volt/Bloog which I think are a bit wider than Boges. And you may need to punch or slot the the steel cartos yourself if nobody sells pre-punched Kanger 3.6 ohms with KR808D-1 threading.
Do the following search at Google - it will bring up previous questions about KR808D-1 carto
tanks
site:e-cigarette-forum.com kr808d-1 carto tanks
You could also try asking the the various tank vendors if Kanger horizontal coils fit in their carto tanks. Clouds of Vapor sells some tanks as well as those cartomizers (maybe not punched though).
And hopefully you have manual batteries.