# Additive Manufacturing for Surgical Planning and Education: A Review
## 2 Workflow
### 3D Printing and Post-Processing  
For 3D printing the models, different technologies can be used. For instance, vat photopolymerization (VPP), also known as Stereolithography (SLA), the pioneering 3D-printer technology for medical purposes, constructs 3D models by layering photoreactive resin material, subsequently solidified by ultraviolet light [10]. This method yields highly precise models but is confined to photopolymers, which can be costly. It also requires the use of sacrificial support material to support overhanging features, and this must be removed in a post-processing operation. Figure 4 depicts heart models manufactured via 3D-printing SLA method [13]. DIW, a type of extrusion-based 3D printing, involves the controlled deposition of materials in a layer-by-layer fashion. In the medical context, DIW 3D printing has shown promise in fabricating complex, patient-specific scaffolds for tissue engineering and regenerative medicine. The ability to precisely control the deposition of bioinks or other materials allows for the creation of intricate structures that mimic the natural environment of tissues. Additionally, DIW has been explored in the production of drug-delivery systems and custom implants tailored to individual patient needs [14]. Figure 3: A screenshot of the editing and mesh preparation step in Magics software (version 25.04). Direct Ink Writing (DIW) 3D printing holds significant promise in the subsectors of surgical planning and education within the medical field. In the context of surgical planning, DIW technology allows for the fabrication of patient-specific models that replicate anatomical structures with high precision. Surgeons can use these 3D-printed models to enhance their preoperative planning, providing a tangible and accurate representation of the patient's unique anatomy. This aids in better understanding complex cases, practicing procedures, and refining surgical approaches before entering the operating room. Additionally, DIW can be employed to create customized surgical guides and tools, improving intraoperative precision [15]. In the sector of medical education, DIW 3D printing contributes by producing detailed and realistic anatomical models for teaching purposes. These models serve as invaluable educational tools for students and practicing healthcare professionals, offering hands-on experiences that enhance their understanding of intricate anatomical structures. DIW facilitates the creation of complex anatomical features, allowing for a more comprehensive and realistic representation of human anatomy. This technology supports the development of educational resources, such as anatomical models and simulation tools, fostering a more immersive and effective learning environment for medical students and professionals alike. Thus, DIW 3D printing stands as a transformative technology with applications in surgical planning and education, ultimately improving patient outcomes and advancing medical training [16]. Powder bed fusion (PBF) employs a powder substrate fused by a powerful laser. Powder layers are successively applied and sintered into the desired 3D shape [14]. Unlike other 3D-printing techniques, PBF for polymers doesn't necessitate support structures during printing, as objects are supported by the unfused powder in the bed. PBF technology is capable of producing metal, plastic, and ceramic items. However, its surface finish is often coarse, and can require post-processing. Figure 5 depicts a 3D-printed prosthetic socket and arm produced using PBF method. Material Extrusion (MEX) stands out as an economical 3D-printing method widely favored by consumers. These printers operate by heating a polymer filament in a printer head and depositing it at specified locations matching the model's shape. The polymer solidifies as it cools, repeating this process layer by layer. Common materials include polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), and other thermoplastics.