A method of manufacturing a surgical instrument or prosthesis and an injection moulded surgical instrument or prosthesis are described. A first material is injected into a first mould to form an interim component. A second material is injected into a second mould containing at least part of the interim component to form the surgical instrument or prosthesis such that portions of the first and second materials are exposed at the external surface of the surgical instrument or prosthesis. The first and second materials are visually distinct such that at least one exposed portion of the first or second material adjacent to an exposed portion of the other material forms a marking which is visible to a user.