## 3 Current Status of 3D Printing in Industry 4.0  
### Technological Evolution in the Context of Industry 4.0  
Additive manufacturing, commonly referred to as 3D printing, is revolutionizing the manufacturing sector and playing a major role in the development of Industry 4.0. The combination of digital technologies, automation, and well-informed decision-making characterizes this new industrial era, building on the achievements of previous industrial revolutions. It incorporates cutting-edge technology including robots, data analysis, artificial intelligence (AI), and the Internet of Things (IoT) [14]. Within Industry 4.0, embedded systems merge hardware and software in industrial operations. 3D printing transforms these systems by enabling flexible design, quick prototyping, and cost-effective production of complex components, leading to more efficient and compact systems. Fast prototyping accelerates development, reducing time and cost to market. A key benefit of 3D printing is its ability to facilitate tailored, on-the-spot manufacturing, allowing for design adjustments to meet individual customer requirements without costly equipment changes. This reduces inventory needs, cuts storage expenses, and supports a sustainable supply chain [24]. In this Industry 4.0 landscape, 3D printing, or additive manufacturing, extends into 4D printing, introducing a temporal dimension to materials, allowing them to alter their shape or properties over time. This development increases the versatility and usefulness of 3D printing technologies in a number of fields, such as the aerospace, dental, regenerative medicine, and automotive industries, where it can be difficult to create complicated geometries and parts using conventional manufacturing techniques. 4D printing introduces exciting possibilities in new industries by using materials that can evolve and transform, offering considerable benefits [25]. In the future, 3D printing is poised to become a key component in the manufacturing landscape of Industry 4.0. Combining 3D printing with technologies such as AI, IoT, and robotics will drive further innovations in embedded systems. Merging 3D printing with digital twin technology enables immediate adjustments and feedback throughout the design and manufacturing stages, enhancing efficiency and minimizing waste. Furthermore, the incorporation of cutting-edge materials in 3D printing, like conductive substances and smart materials equipped with sensors, offers the potential to develop embedded systems that are more advanced and capable of self-diagnosis and self-repair [24]. In composite manufacturing, 4D printing interacts with Industry 4.0 technologies like AI and IoT, significantly improving adaptability, precision, and efficiency. Similar to its application in 3D printing, AI in 4D printing is used to develop generative designs, model and predict robotic arm movements, and ensure the quality control of printed elements [26]. AI algorithms analyze real-time data to optimize the printing process, allowing materials to adjust their shape or properties over time. Meanwhile, IoT enables connectivity between systems, where 4D-printed components with embedded sensors can monitor their own performance, communicate their status, and automatically adapt to external conditions. In recent years, cloud-based 3D and 4D printing systems, powered by AI, have further advanced the manufacturing process by optimizing productivity, facilitating knowledge transfer, enhancing collaboration, and supporting universal software development. These AI-driven systems streamline printing operations, allowing for real-time adjustments and improving the management of complex manufacturing tasks [27]. By integrating AI and IoT, 4D printing not only enables the production of more intelligent, adaptive, and self-healingmaterials but also reduces waste and enhances overall production efficiency, aligning with the goals of Industry 4.0.