Roof boxes are external storage devices attached to the roof of a car to expand its loading capacity. They are primarily used for transporting bulky items such as skis and camping gear. In manufacturing, lightweight properties, weather resistance, strength, and aerodynamic performance are emphasized. The main materials are ABS resin and FRP (Fiber Reinforced Plastic). For ABS resin products, vacuum forming, which is suitable for molding large parts, is frequently used. For FRP products, hand lay-up and RTM (Resin Transfer Molding) are sometimes employed. After molding, trimming, drilling, surface treatment (such as UV coating), and the assembly of components like hinges, locking mechanisms, and gas struts are performed. High quality requirements include safety during driving, waterproofing, impact resistance, and anti-theft features. Aerodynamic performance evaluation using CFD analysis is also conducted from the design stage.