dry ice, ice cream stores, .75 per lbs, yeah yeah, and co2 to fill in the chamber, oh well, I was thinking, and I knew theres something easier than that.. yall can do this really easy, all ya got to have is empty one gallon milk plastic carton.. add lot of sugar, maybe half or 2/4 then add water, and make a little hole for the tube like usually go to the buds area in flowering room. the hole should be near the cap top. now the final process, drop the yeast in the milk carton, it will begin makin co2 itself less hassle than dry ices!! put em in the flowering room and plug in the tube to the hole that goes to around the buds, I hope I helps. those is brillant I ever though of!