This is the tornado box I made for my school project. It uses dry ice and a 24 by 12 box to show the vortex of a tornado. The instructions for making the box and the materials you will need are here: http://www.tornadoproject.com/cellar/... We used the plexiglass from a poster frame from walmart. They are where the frames are. It is the cheap poster frames with a thin piece of plastic for the front. You can then cut the plastic with a utility knife. We also got a desktop fan from Walmart. Make sure it takes batteries so you don't have to worry about a cord. Plus make sure that is not the very smallest ones, they don't suck up enough air. You will face the fan upside down on the top of the box, after you cut a hole about the size of the fan opening. This will suck the air out of the box causing the vortex. You must cut the air slits like the web page shows. You could also use a cool mist ultrasonic humidifier or a hot plate and boiling water if you don't want to use dry ice. Fun to watch!