The importance of clinicians having a thorough understanding of 3D printing technology from the engineering perspective is being emphasized in recent literature, as well as clinical practice. As long as patients’ needs become more demanding and possibilities offered both by software and hardware increase, it is essential for the surgeon to understand the main technical aspects related to additive manufacturing technologies, for the most conscious selection of the appropriate technical aid or implant. In this regard, this chapter explores the world of additive manufacturing with emphasis on the different production processes, which are explained in detail. A thorough knowledge of 3D printing processes is essential also to understand the application of regulations and to appropriately set a point-of-care laboratory as seen in subsequent chapters. The clinician should therefore focus attention on the production technologies elucidated in this chapter, apprehend their mechanisms, and critically appraise them when opting for a 3D printed tool or patient-specific implant in surgery.