Simple steps to make a
poor bastard CO2 generator
Get some
dry ice Click here if you need help to find someone who sells dry ice in your area make sure to select "Penguin Brand Dry Ice Retailer" on the search thingy
Get some kind of container like a bucket, big bowl or something like that
Put some water in the container and then drop in a piece or two of dry ice (depending on the size of your cab/room)
Turn off exhaust fans[s]
Point small fan towards container on low to help mix the CO2 in your room instead of it all sitting on the floor.