||Fused Filament Fabrication (also known as 3D printing) is a routine additive manufacturing technology widely used in industry, science and hobbies. Despite numerous advantages, FFF-made components often suffer from insufficient mechanical performance. The lower mechanical performance is typical of middle- and hobby-level FFF devices. Proposed research is aimed to the optimization of morphology, micro- and macromechanical properties of selected polymers prepared in three different ways: (i) by means of standard processing techniques (such as melt mixing and compression molding), (ii) by means of commercial FFF devices, and (iii) by means of modified FFF device, which could produce samples with improved mechanical properties. The modified FFF device will work with the melted filament in the environment of atmospheric-pressure plasma. Plasma serves as a source of highly-reactive species (excited radicals, molecular ions, and atomic ions). These species cause partial break of polymer chains, followed by cross-polymerization or co-polymerization if co-polymer is added. Prototype of dedicated equipment containing experimental printhead and RF power generator for plasma generation will be developed during the project in order to investigate feasibility for practical application.