a composite structure , and method of manufacturing it , having a specified width , length , and height defining a top and bottom the composite structure . the composite structure includes a three dimensional structural core constructed of a polymer with a first series of a geometric pattern repeated along its length . the structural core also has a second series of the geometric pattern repeated along the width thereof . the geometric patter may be a sinusoidal curve or a substantially pyramidal shape . the composite structure also includes a first reinforcement layer made of a polymer positioned above the structural core and bonded thereto . it also includes a second reinforcement layer made of a polymer that is positioned below the structural core and bonded thereto . the composite structure may also include a decorative layer above the first reinforcement layer , an acoustical batting layer positioned between the first reinforcement layer and the structural core , and may include fire retardant chemicals .