I have been using 1 gallon jugs with the top and bottom cut off as killing cones. It works fine but the plastic is rather weak and they can be too small for bigger birds. I am trying to think of other ideas for home made cones and think a thicker plastic, larger bottle would be better than a traffic cone. Jaku's cones look great but $50 for two (shipping included) is just more than I want to spend right now. Maybe a 5 gallon water jug from a cooler? Something 2-3 gallons would be ideal.