Embodiments of the present disclosure relate to design methods for designing a mandrel for hammering, pressing and/or pushing an implant into position in a recess made in a joint and firmly attach the implant to the bone of a patient, the mandrel comprising a contacting surface adapted to be in contact with an articulate surface of the implant to be inserted, the method comprising designing the contacting surface of the mandrel to fit the articulate surface of the implant in that the contacting surface of the mandrel has a cross-sectional profile corresponding to the cross-sectional profile of the implant.
