A process is provided for casting a mounting which is attachable to a human body and which takes the form of a prosthesis socket or of an orthosis part. The mounting includes a reinforcement in the shape of a grid or frame located in the core region of the mounting and is surrounded by a lower polyurethane sublayer and a superposed polyurethane sublayer. The process includes a) providing a first spacer material to be soaked with a incompletely reacted polyurethane, b) producing a reinforcement thereon, c) removing the reinforcement, d) casting the lower polyurethane sublayer by saturating the first spacer material with the incompletely reacted polyurethane, e) superimposing the reinforcement on the polyurethane surface of the lower polyurethane, f) applying a second spacer material to be soaked with a partially reacted polyurethane and g) casting the superposed polyurethane sublayer by saturating the second spacer material with the incompletely reacted polyurethane. The first spacer material is positioned at the lower polyurethane sublayer. The second spacer material takes the form of the superposed polyurethane sublayer. The polyurethane sublayers come into contact and both sublayers bond reactively and enclose the reinforcement.