I had a roll of aluminum sheet sitting here, and I needed to slaughter a turkey. I snipped of 34 inches, made a cone roll, which created 2 "horns" on the top, drilled it and riveted it up the middle, then smaller rivets for the inside flap and outside flap, trimmed the "horns" and voila. Homemade killing cone. Cost me zero deniro as I had everything on hand, but you could easily do it with tin also or even an aluminum flashing. Rivets are cheap. So don't go buy one, just make one!