A device for covering and/or reconstructing a bone defect site includes a cap (molded shell, rigid shell, molded body) having a rim and at least one fixing device for fixing the cap on a bone. The cap has a dimensionally stable (rigid) nature. A wall of the cap facing the bone defect or a wall of the cap facing away from the bone defect corresponds to the shape of the regenerated bone, at least one positioning device being located on the rim of the cap. A method produces a cap for a covering device for a bone defect site.
