3D printing (3DP), also known as additive manufacturing (AM), is a popular method used in Industry 4.0 that involves using machines and pens to create customized and complex 3D objects from a digital file by layering materials. This technology is widely used in industries such as aerospace, automotive, healthcare, and consumer goods for prototyping, rapid tooling, and production of end-use parts. 3DP offers companies a low-risk, low-cost, and fast way to produce prototypes, allowing them to test new products and speed up development without expensive models or specialized tools. Machines are more suitable for creating larger and more complex objects with high accuracy, while pens are better for smaller and simpler designs. Machines can be expensive and require training, while pens are more affordable and easy to use. Overall, AM with 3DP has provided new possibilities for designers and manufacturers. This chapter will further explore different printing methods, materials, advantages, limitations, software applications, potential uses, and future prospects of this technology.