We get it all here at JIS Central. Mike Howden explains how to make your very own smoke machine...
It is fairly easy to make a dry ice fogger. Dry ice fog is not as good as chemical fog but in a pinch it will do. The main draw back is portability. This unit is not easy to move around and takes time to get it running. Here's what you need:
The heater mounts into the base of the drum, a hole is drilled out of the side to mount the electrical connections. Some kind of seal has to be made around this hole (silicone, or fiberglass are recommended) At the top of the drum a 4 inch hole is cut and the flange is mounted around it. This can be rivetted on and sealed as above.
If you have the ways and means to cut a hatch door in the top of the drum it is a good thing.
A hole is cut in the top to except the fan and the fan is mounted (metal tech screws work well)
The dryer hose is attached to the flange with a worm gear clamp (or a ring clamp)
You fill it about half way up with water and plug it in. It takes a while to heat up but when it gets steaming drop in a couple of chunks of close the lid and turn on the fan.
The key to this project is finding as many of the parts as you can, if you take your time and look around you should only have to buy the heater and the fan.
If you want to get fancy you can rig a steel basket that you can raise and lower inside the drum so you can retrieve the dry ice and stop the fog. Otherwise once you drop in the ice it fogs until there is no more ice.
If you know anybody in technical theatre they can help you out with this.
Have fun.