"La Chaise" consists of two paper-thin fiberglass shells glued to each other but separated by hard rubber discs; the intervening space was filled with polystyrene foam. Charles and Ray Eames left the plastic shell untreated. The base is made of five in part angled metal rods inserted into a cross-shaped wooden structure. The space left open between back and seat is not technically necessary, but instead purely a design element. The intention was to emphasize the chair's lightweight visually by perforating the otherwise large volume of the shell.