Yes the PVC pipe would be on the heavy side. PVC pipe can be molded. The outer half of my intake ducts are moulded from a piece of PVC pipe that was cut in half, waxed, and sprayed with PVA. I then covered it with lightweight fiberglass and then one layer of Kevlar. In hindsight fiberglass only would of been better because it would of eliminated small pinholes in the Kevlar cloth. You still need to stiffen the intake because of the suction made by the fan. I steamed balsa by putting it on a plate with water and the microwaving it for about 5 minutes. I then glued two strips per side and that solved the problem. In the future I will laminate foam to the outside of the inlets to stiffen them. The inner part of the duct was made on a homemade mold that eliminates the need for the spinner.