Abstract: A door or other structural panel of the type which has a pair of opposed, congruent sheets spaced apart by a frame to define a separation space between the sheets which may be filled with a core, such as foam. The edge of each sheet has a zig-zag portion which defines a ledge on the outer side of the sheet and a ridge on the inner side of the sheet. The frame member between the sheets at each edge has on each of two sides a projecting flange and a projecting hook which interlock with the zig-zag portion of the sheets to create a mechanical engagement between the sheets and the frame member. The flow of liquid foam into the separation space is controlled by a rib projecting inwardly from the sheet and by a resilient foam block slightly compressed between the sheets. Methods of manufacturing such panels are provided, including by sliding the beams onto the sheet edges and tapping the beams into a rigid state, and by employing temporary frame members which can be removed and re-used after the foam hardens.