an exterior autobody part of reinforced plastic intended to be mounted on a motor vehicle . the expression “ exterior autobody part ” refers to the autobody part being entirely or partly visible when the motor vehicle is viewed from the outside . furthermore , the invention relates to a method and an arrangement for forming such an exterior autobody part . the exterior autobody part according to the invention comprises a number of functional layers , including load - bearing layer and surface layer , intended to provide the properties which are required for the application , and is characterized in that load - bearing layers comprise fiber - reinforced thermoplastic which forms internal cavities and / or that one or several recesses has / have been created in surface layers and load - bearing layers and that surface layers and load - bearing layers together with cavities and / or recesses thereby provide a load - bearing material structure . examples of properties essential for the application are low weight , high stiffness , and durability , recyclability and visual properties . the invention can be applied within the field of externally visible motor vehicle parts , for example boot lids and wind deflectors .