Modern technologies of additive manufacturing (or 3D-printing), which enable the creation of very complex geometries, have strongly stimulated the development of the industry. This is based on the numerous advantages of additive manufacturing compared to conventional production methods, especially the speed of production, the simplicity and lower cost of manufacturing very complex products, the possibility of using different starting materials, and environmental acceptability, given that there is mostly no waste material generated or their formation is minimal. To date, numerous additive manufacturing techniques have been developed differing from each other in the materials used, operating principles and device configurations. According to ISO/ASTM 52900:2021, the standards of additive manufacturing techniques are divided into seven categories, and one of the most widely used is the fused filament fabrication (FFF), which is based on the extrusion of the corresponding material. This technology bases its popularity on the possibility of making very complex products or embedded parts in a very short time. It is possible to use different starting materials depending on the requirements of the expected final product. Thanks to its numerous advantages, this technology has an important application in the field of catalytic reaction engineering. In this article, the comparative advantages of additive manufacturing technologies for the production of complex structured and monolithic designs of catalysts/reactors are analyzed in comparison to traditional extrusion processes. Special emphasis is placed on fused filament technology. Different types of 3D printers, suitable materials for application, utilization and the main challenges that may arise during the printing process, along with possible solutions are described. In the last part, an example of the application of FFF technology is given.