I like my thumbdrive cases for batteries from Case Logic. Three pockets per side, each one holds two CR123s, 3 AAs, 4 AAAs, or a bunch of properly packed button and coin cells. And there is enough room to put in a cut down paint ball tube to hold two more 123s at the top with cotton between them, or a TONNE of button cells if they'll fit.

The middle one.


They are like 5-6 bucks at Wally World, more elsewhere.