The wingtips are made of 10mm-thick balsa and are fitted to the faired wing shape. A 1mm-thick plywood triangle is attached to the balsa piece. 2.The keel is made in two copies from 5mm balsa. To stabilize the structure, a lining and 1mm plywood are glued onto the epoxy resin. 3. After covering the two keels with film and painting the tips, they are finally ready.