Abstract: A method for fabricating a grid-stiffened panel which incorporates a network of fluid channels and passageways into the ribs and face sheet is described. The method is comprised of a base tooling assembly, an expansion tooling assembly, a composite prepreg, plugs, a face sheet and a network of valves and pumps, wherein the prepreg is draped over said expansion tooling and assembled with the base tooling assembly to form a rib structure. Channel plugs are placed therein such that gaps between adjacent expansion tooling blocks are filled, and the entire rib structure assembly is autoclaved. The face sheet may be comprised of a plurality of layers, whereby channels are machined into the lower layer(s). The upper layer(s) are bonded to the lower layer(s) to seal the channels, and said face sheet is bonded to the rib structure.