A honeycomb-shaped panel is formed from a plurality of generally sinusoidally shaped strips of molded fiberboard material each having spaced, oppositely directed flat peaks, the peaks of adjacent strips being secured together to form a plurality of hexagonally shaped cells extending perpendicular to the surfaces of the sheet. The strips may be cut from a single sheet of corrugated fiberboard sheet material and then secured together to form the honeycomb panel, or a plurality of such panels may be secured together face to face with their ribs aligned to form a stack, and selected cuts may be made through the secured, stacked panels to form a plurality of honeycomb panels of desired surface shape and height dimensions. The strips forming the cells are substantially rigid and resistant to collapse of the cells, and form a substantially rigid core when assembled between two flexible fiberboard skins, while the panel is bendable to adopt a desired panel curvature.