Stability is one of the core requirements and at the same time an important potential weak point for components manufactured in layer-by-layer 3D printing such as Fused Deposition Modelling (FDM). One key to greater stability is to improve the adhesion between the individual layers, and the researchers at the Fraunhofer Institute for Surface Engineering and Thin Films IST achieve this through targeted chemical modification of the surface by using atmospheric pressure plasmas. Various plasma sources have been developed at the Fraunhofer IST specifically for this application, which can be integrated into the 3D printer and thus enables the individual layers, which are often no longer accessible later, to be treated during the printing process.