Segmentation is the first step in the creation of specific anatomical models and customized patient specific medical instrument (PSI). It involves the precise isolation and extraction of intricate anatomical structures from medical imaging data, such as CT scans or MRIs. This process is essential because it allows healthcare professionals and engineers to focus on specific areas of interest within a patient’s anatomy, whether it be a complex organ, a bone structure, or a vascular network. Once segmented, this data becomes the foundation for the subsequent stages of 3D modeling and printing. Segmentation is the gateway to the world of personalized healthcare.