A flexible, bendable organic decalcified or partially decalcified bone, cortical or cancellous, adapted for use in augmentation or repair of animal skeletal structures comprising a continuous plate or sheet of natural bone, as well as dermis is described. The thickness, flexibility and tensile strength of the construct is such as to allow it to be shaped and contoured without damage to it. The composition is ultimately remodeled by the body, thus obviating the need for additional surgical intervention. The clinical indications for the use of the invented construct are many, but are particularly prominent in dentistry, oral and maxillofacial surgery and implantology. It is particularly useful in the maxillary sinus augmentation. A unique new method, different from previously described methods for the preparation of the disclosed constructs, is described.