Abstract: A honeycomb structural material formed from flat sheet material 60 by establishing a plurality of channels along parallel channel fold lines 68 and reverse channel fold lines 74 and reverse channel cuts 70. A spaced array of holes 66 are cut in the top surfaces 86 of the channels with triple point fold lines 72 formed in top surface 62 and side wall fold lines 74 formed in bottom surface 64. With all fold lines formed flat sheet 60 is folded into plurality of channels and compressed along the axis of the channels to form the honeycomb structure.

Abstract: A ski construction for cross-country skiing is provided including front and rear tandem ski sections pivotally joined together by an offset hinge at their adjacent ends for relative angular displacement about a transverse axis closely adjacent the undersurfaces of the sections between predetermined first positions with the undersurfaces substantially coplanar and variable second positions with the longitudinal undersurfaces defining an included angle greater than 180.degree.. Spring structure is operatively connected between the sections for yieldingly biasing the sections from the variable second positions toward the predetermined first positions and is in the form of a straight structural brace bracing the ski sections against angular displacement toward the second positions. The spring must be laterally deflected intermediate its opposite ends from the static brace defining straight position thereof to allow angular displacement of the ski sections toward the variable second positions.