Dowel type control rods are the simplest and cheapest way to do it, unless I'm putting together a big gasser, I like to use the dowel style, just for convience and strength. Carbon is good and plenty strong, but the joint where the metal connects to the rod must not stress the outter carbon tube, otherwise it will crack the carbon fiber tube and fail. Nylon is good for small aircraft that has light control surface loads, unless you buy the big honkin huge nyrods, for the arrow shaft method, buy the dave brown end fittings and plug the wire into them. On your trainer, just do dowels with wire method, I perfer wrapping them with thread, heat shrink tends to be a little weak for my liking, but that's my own oppinion.