A new molding technique of the Acryl-resin Marlex-mesh sandwich method is described. After the wide extirpation of the chest wall, the defect size tends to grow up more larger than the specimen. For making a just fit size prosthesis, we cut off a cardboard as the same size as the specimen and the Acryl-resin Marlex sandwich is molded from the cardboard. Other some know-how are in the text.