Method of manufacturing a product comprising fiber reinforced polymer material, the method comprising the steps of: providing 10 carbon fibers being embedded in a thermosetting resin, heating 20 the thermosetting resin up to its cure temperature by a current flowing through at least a part of said carbon fibers, letting convert 30 the thermosetting resin to a thermoset polymer. The invention is further directed to a device for performing the method and to a composite sandwich panel structure manufactured according to the method.