A corrugated panel having a core between two faceplates where the core andaceplates are comprised of curable material and where the core is comprised of undulate strips that are disposed in parallel relation to each other. The strips define peaks and valleys connected by diagonally-extending segments that have non-planar cross-sections. The peaks and valleys in adjacent strips are 180 degrees out of phase with respect to each other. The faceplates and the strips are joined at the peaks and valleys.A method of making a corrugated panel assembly comprising the steps of providing upper and lower faceplates and a core of strips, all made from curable material. Mandrels and inserts are used to form the strips into alternately-arranged peaks and valleys that are interconnected by diagonal segments where the diagonally-extending segments have non-planar cross-sections. The strips are 180 degrees out of phase with respect to each other. The mandrels are replaced by granular particles and the assembly is cured.