Customised implants manufacture has always presented difficulties which result in high cost and complex fabrication, mainly due to patients' anatomical differences. The solution has been to produce prostheses with different sizes and use the one that best suits each patient. Additive manufacturing (AM) as a technology from engineering has been providing several advancements in the medical field, particularly as far as fabrication of implants is concerned. The use of additive manufacturing in medicine has added, in an era of development of so many new technologies, the possibility of performing the surgical planning and simulation by using a threedimensional (3D) physical model, very faithful to the patient's anatomy. AM is a technology that enables the production of models and implants directly from the 3D virtual model (obtained by a Computer-Aided Design (CAD) system, computed tomography or magnetic resonance) facilitating surgical procedures and reducing risks. Furthermore, additive manufacturing has been used to produce implants especially designed for a particular patient, with sizes, shapes and mechanical properties optimised, for areas of medicine such as craniomaxillofacial surgery. This work presents how AM technologies were applied to design and fabricate a biomodel and customised implant for the surgical reconstruction of a large cranial defect. A series of computed tomography data was obtained and software was used to extract the cranial geometry. The protocol presented was used for creation of an anatomic biomodel of the bone defect for the surgical planning and, finally, the design and manufacture of the patient-specific implant.