While there are other threads on the topic of carrying single and multiple 123's (did you do a search?), they seem to boil down to the following:
- do not carry loose 123's (or any battery) in your pocket. Why? They can easily short out against any metal object in your pocket and will get warm. And then hot. And then very hot. And remember what is on the opposite side of the cloth in your pants' pocket. Woooo Woooo! "Mommy, look at that man over there doing that funny dance!"
- Avoid any situation where you can short out batteries. Lithiums can not only get hot, they can go BOOM!
- SF spare carriers are great and not all that expensive. Safe carry of both batteries and lamps (and the lamps are too expensive not to carry in one!).
- Cheap 123 carriers:
-- APS/Advantax film cannisters will carry 2 snuggly and are usually free if you ask for empties at a film processing center. Give a good shake to get the batteries out. Hey, what do you expect for nothing? They do work well, though.
-- Canisters for bottles of nitro tablets (used for heart patients) are perfect for keychain carry of a single 123. I got one for under $5 at RiteAid. They are usually waterproof, too.
-- 2 cells will fit in most plastic match cases. Less than a buck for each case. Available at sporting goods stores, MallWart, etc. They might rattle around, so if you don't want to listen to that, place a bit of foam rubber or styrofoam in the bottom. These are also usually waterproof.
-- Some cigar tubes are the right size. Just avoid the metal ones or else place a piece of electrical tape over the terminals to avoid shorts. Don't use glass tubes if you plan to carry them on you -- snap! ouch!
Hope this helps.