A door panel 1 has a peripheral frame 10 of extruded aluminum and a honeycomb core of plastics material tubes 11. An outer skin 2 of fiber-reinforced polyetherimide material is recessed with a pattern 3 formed in a preliminary operation of vacuum/pressure forming at elevated temperature. An inner skin 4 is plane. Edge channel members 5 of similarly formed, but thicker material are arranged around the edges of the door, enclosing the aluminum frame. A non-woven, polyester based scrim 6 extends across either side of the core and over the flanges 7 of the edge channels.For bonding of the core, skin and edge channels together, the assembly is placed in a jig and compressed at elevated temperature in a heated press. The core is crushed at the recessed pattern 3 and the scrim melts and acts as a hot melt adhesive. On cooling of the press platens, the assembled door is removed from the jig.