I had LOTs of fun the other day making a cooler for my
fog machine. We cant afford dry ice, so I too an old piece of ductwork and lined the inside with a styrofoam type insullation. I then put several gallon zipploc bags (well sealed) full of ice inside. I ductaped over the top half of the exit end (the duct was lieing down on the
ground) so only the coldest air on the bottom of the shaft would come out. At the other end I put my
smoke machine, and two computer cooling fans blowing into the shaft (with a few stratigic pieces of ductape to keep air and
smoke from comming out the wrong end). (I took an old AC to DC
power supply from an old CD player or something like that that was the same
voltage and amperage as the fans I needed and used that to spin the fans, although i just as easly could have used a 9V battery.
This created a very cool looking layer of
fog that stayed fairly low for a little while anyway. The longer the
fog was out of the tube, the more it warmed up and floated up. It was not too hard to
build and might work well. (it certainly can provide alot more volume of
fog then I have ever been able to get out of Dry ice) There are plenty of websites on the internet that will show you how to make something similar with a cooler, (i didnt have cooler to cut up, so i made my own

) just do a google search for "
fog machine cooler" or something like that (no ""s in the search) Have fun!