I copied these from the DC3 skis with the little wings on the back. Built for last yrs. flying. Had to take some of the curve off the front as they acted like up elev.and flew around with the skis almost pointed straight up.
These are on a Zoombi bipe Just got through making a set for the Flash 3D. They do work very well with no strings or rubbers attached. These are made from EPP foam with the wings made from $ Store foam and 1/16 carbon on the front edge of the wing for stiffening with hockey tape on the bottom to toughen them up and give a slicker surface.