A device for covering and/or reconstructing a bone defect site and a method for producing a cap of a covering device for a bone defect site, wherein the device for covering and/or reconstructing a bone defect site consists of a cap (moulded shell, rigid shell, shaped body) and of at least one fixing means for fixing the cap on a bone. The cap is distinguished by having a dimensionally stable (rigid) nature, and a wall of the cap directed towards the bone defect or a wall of the cap directed away from the bone defect corresponds to the shape of the regenerated bone.
