A four-year-old is smarter than that. However, if you want to be a total moron and make one of these to blow off your fingers, go ahead. See if I care. I don't. Don't try this at home yada-yada-yada. But here's a video showing you exactly how to do it on a smaller scale on Google Video. Sort of a how-to for morons:
http://video.google.com/videoplay?docid=7598578066703715064&q=dry+ice+bomb
Nice huh? Well, check this one out where it doesn't go according to the plan:
http://video.google.com/videoplay?docid=3989534566066145643&q=dry+ice+bomb
Morons to the max. BTW, making an explosive device in my state is mucho bad no-no and you will get taken away by the authorities. Don't know how they feel about it in yours but they probably wouldn't like it either. You are a moron if you try this. You are a super moron if you try this and hurt yourself or some random four-year-old.
Morons.
You could skip blowing your fingers off by just watching vids on Google instead:
http://video.google.com/videosearch?q=dry+ice+bomb
You should be more like Cantrip.
Twitchy: "I pulled a Cantrip . . ."
GivePeaceAChance: "If the Tempest had nipples, I'd pinch that shit."
Xylicon: "I'm about to deliver my [Richard] in your face for posting that stupid shit. "
WDF?: "He keeps reaming me... night after night... I'm rather sore."
GivePeaceAChance: "OMG MY NIPS ARE HARD"
llenta: "cantrip, you fail!!!"
Filliam H. Muffman: "i'm on top of dick"