Wooden Wings
Airplane wings work because they have an airfoil shape. This means the wing is curved so that as the plane moves through the air a pocket of air forms underneath the curve of the wing, giving the wing an upward lift.
The light weight of balsa wood makes it a good material for model planes. A balsa wood frame is constructed and reinforced with wooden spars that match the shape of the wing curvature. Thicker wooden sheeting is often used to reinforce parts of the wing exposed to the most stress.
The balsa wing is covered with a heat shrink plastic material. A tool that looks like a small steam iron heats the material, causing it to shrink to the balsa frame.
Aluminum
It is not unusual for a model plane builder to spend many hours building one plane. According to Model Airplane News, aluminum pop cans are a good source of wing covering material. The metal is thin and easily cut to form the sheets needed to build a plane.
The can aluminum is cut to the sizes needed and riveted to the plane body. This can be used to make all the fuselage surfaces of the plane and painted for an authentic-looking replica.
Foam Wings
Styrofoam is the answer for many model plane builders. It is very easy to shape wings and other plane components out of this sturdy, lightweight material. Styrofoam wings are much stronger than balsa and lighter than plywood.
Models can be shaped from blocks of foam or built using recycled Styrofoam containers. Foam deli trays and restaurant takeout boxes are used to make wings for simple gliders or complicated remote control flying machines. If foam wings break in a crash they can easily be repaired or replaced at little to no expense.