I used carbon fiber with the dowel inside it. This is a big wing, and snap rolls put tremendous pressures on the wing and the contact points. I also discovered that the ruder helper was to much help at higher speeds, so either a very strong servo or a revamping of the helper size was necessary. I opted for both because comming out of a spin at higher rates of speed was scary, especially close to the ground. Otherwise, this is one really fun great flying machine. Oh, one other thing, I slowly peeled the the covering back and "GLASED'' the center section of the wing, just in case. HAVE FUN "FLATHEAD 4"