I can't speak for other carts, but the cigar ones also come in these neat little 1/3 cigar shaped tubes, which should keep things dry even with refils, and in the shimmers case even fit the batteries.
The caps are a little loose, so in practice I wouldn't put them in my case cap down (like in my pics) but cap up should be fine.
Speaking of cases: soot I get your point, but for general 'going out' I want something smallish and comfortable in my pocket, not man-bag size

especially if I'm on the bike.
3 bats + 3 carts (one of each in the shimmer) + the cigar itself should be enough for a day and will fit in my leather?
For around the home I have put in a 'hint' to my wife for a nice solid wood box that will sit unobtrusivly on the coffe table or desk - something in rosewood or laquerwork would suit my taste.
However, for trips upto Scotland in the jeep (my preferred hol destination) I can see where a good bag like the others might be useful... food for thought.