Here is a way to easily construct a true, cambered airfoil from Dollar Tree (Readi-Board) foamboard, hot glue, and packing tape. The technique allows making the entire wing, including the control surfaces, from one contiguous piece of foamboard. These wings can be used singly or joined with a dowel or carbon arrow shaft for wingspans up up to 90". Recommended chords are 5" and 7" for the airfoil component, plus whatever control surface you desire.
Within this overview video are links to more detailed videos on each step. If you would like to see more about any particular step, click on the link. If you are watching in FliteTest the linked video will open in the player window. If you watch on YouTube directly, a new tab or window will open with the linked detail video, leaving the original video paused in its own tab or window.
* The color balance on this video is pretty horrific due to white balance problems with my video camera, different each take, and only partly corrected in editing -sorry for that.