Tornado tube couplers cost between $5 and $10 purchased online. This video shows how easy one can be made for free at home. Using 2 16 oz. plastic soda bottles, a drill with a 1/2' bit and a flame it takes a few minutes. Use plastic bottles that have a flat top, not the rounded ones. Drill 1/2" holes thru the 2 plastic bottle caps. Melt the 2 cap tops over an open flame. I used a gas stove burner. A wisp of smoke coming from the melted cap tops is a sign that they're ready to be put together. Cool the joined tops under running water. Remove the labels from the bottles fill one up to an inch below the top. Connect it all together and you're finished.