What I need to find is a small but great tank that I can build coils for! Once I retire I can't be buying blister packs all the time!
My friend, the tank you speak of is the Kayfun Lite, Kayfun Lite+, or Kayfun Lite+ V2...aka KFL, KFL+, or KFL+V2.
They're pretty much all three the same, minus some slight changes, mostly cosmetic.
Also, all three are commonly referred to as just "KFL", though some folks like to specify the "+" & "+V2"...
Widely available, easily identified as authentic (when comparing to even the best clones...if you care about that sort of thing), and the whole accessory aftermarket for vape gear was practically built upon making accessories and options for the KFL. Not to mention, at least 90% of atomizers on the market today, incorporate some version of the Kayfun design and/or principles. It's almost like the Big Bang of vaping!
This is what a full sized KFL/+/V2 looks like:
(The first "Lite" had a different drip tip)
Here's one of mine, with a custom tank, that makes it as small as possible:
(Tiny Tank from SteamTuners)
Granted, this tank reduces juice capacity, but I like the smaller size and don't care about frequent refills.