Hopefully this doesn't post twice.

My theatre company did Hairspray last year and we used these: http://www.filmtools.com/diffusionincan.html

They worked great! The only "issue" was that the nozzles spray straight up instead of out of the front like a hairspray can actually would. Honestly none of our audience noticed. And as long as people don't go crazy spraying it, we were able to get 14 shows plus around 6 rehearsals out of each can and STILL had fog left in them. Just saying because we thought we would go through them like crazy and bought 3 cans per actor and got stuck with them - we have since used them in other things.

so, we're in tech week! My director only has a few people with functioning cans, not crowds of people, so I'm not so concerned with running out - the only 'big deal' with the 'smoke in a can' that I got is that they are a smaller can, so I had to find a tube that the can would fit inside as a slipcover - so far, they're working well, one actor pulled the can out of the slipcover when he pulled the cap, but it was his first time doing it, and it hasn't happened since.  I've warned my cast not to spray the smoke in confined spaces as it was specifially developed for testing smoke detectors - so far, so good - now on to the scoreboard for the Miss Hairspray Contest -