You can make a very simple, yet effective fog generator for use with an air cannon, or for use at parties or with laser experiments. The fog generator is made from an ice chest. I use an inexpensive polystyrene foam (Styrofoam) ice chest that cost about three dollars. You will need:
A styrofoam ice chest,
Some 4 inch dryer hose,
Some duct tape,
A serrated knife for cutting.
Using the serrated knife [NOTE: Not recommended for children!], cut a hole large enough for the dryer hose to fit through the lid of the styrofoam chest. Do the same to your air cannon as well (see Giant Air Cannon for a description of how to build an air cannon).
Use duct tape to secure the hose to the lid and to the air cannon. Tape the duct on the inside of the lid as well as around the outside.
Using the Fog Generator
Fill the fog generator with very hot, but not boiling water. Add some chunks or pellets of dry ice and replace the cover. Soon fog will begin filling your air cannon or issuing from the dryer hose.
That’s it! When the fog generation diminishes, recharge with hot water and/or more dry ice.