Additivemanufacturing (AM), also known as rapid prototyping or 3Dprinting, generally refers to techniques that produce three-dimensional parts by adding material gradually in a layer by layer fashion. In this sense, AMdiffers fundamentally from forming and subtractive techniques. This special issue intends to put together research and developments in AM, particularly related to new manufacturing processes and/or to alternative feedstock materials and products. Polymer and metal-based raw materials and products have been extensively investigated inAMtechniques. Recently, ceramic, glass, and composite materials have been additionally used both in commercial and in innovative AM processes. The material compositions and processing steps used for shaping or finishing the structure of AM products are responsible for final properties and performance. Recent advances in sensors, micromechanics, computational modelling, and simulation have enhanced AM technologies. As complex parts become easier to build and the equipment and skills needed to build them become more and more common, innovative approaches are achievable. Additionally, this evolution opens up new fields of application,moving it from being a prototyping tool to a final productmanufacturing process (rapidmanufacturing). This special issue explores the development of new products and applications throughAMprocesses. Selected investigations contributed to this issue with original research that analyze feedstock materials, process parameters, and their effects onmechanical, physical, and other properties in prototypes or customized parts fabricated by AM techniques. The topics presented in this issue include diverse materialsmanufactured by representative AMprocesses, as summarized below: