You can only fit it in one backpack.
I think it's a stupid idea, but here you go. They go off right away. Think about it; if you were in a real fire, you wouldn't want a thirty-second delay on the alarm. Here's some advise for you, hope you and your friend survive the day. Dress as normal as possible. You want to blend in. Nobody fingerprints a fire alarm! Wear gloves only if most people are. Try to stand in a clump of people and pull it when they aren't looking. If you're with a group of people, don't move after you pull it. Just act like it's a fire drill. If you're alone, edge a few yards away, then act like it 's a fire drill. Do not run. You 'll look guilty. Don't stand near a teacher. Don't look guilty. Practice your Who, me? look in the mirror. Do what you usually do during a drill. If you normally talk with friends even though you shouldn't, do that. Don't stray from the norm. Tell nobody what you're going to do, not even your friend if you haven't told him yet. You don't want somebody to rat you out. Don't talk about it afterwards. If you are caught red-handed or ratted out, spill your guts. Don't fight for a lost cause. Have some fun!
According to the Material Safety Data Sheet (MSDS), the resins, hardners and accelerators are not cancer causing agents. The vapors and skin contact can cause severe eye or skin irritation or lung irritation. Proper ventilation should take care of that problem. As always, it is a good idea to wear eye protection of some sort. I have used the premixed (like a large syringe) stuff and the stuff where you buy the two separate cans. The only time I had a problem, is I got it on my hands and wasn't wearing latex gloves.
