In the recent years the fused deposition modelling (FDM) became one of the most popular rapid prototyping (RP) techniques. With this method we are able to build a composite object layer-by-layer. However, because only a limited number of materials, such as thermoplastics have been used as a feedstock for FDM, the final products have limited mechanical properties. The fiber reinforcement materials can significantly increase the mechanical properties, such as stiffness and strength, of the final product, especially in the direction of the filament. Nevertheless, the mechanical properties of the final part on the transverse directions still relay on the poor adhesion between filament layers. In this study the main purpose is to investigate the 3D printed object structures and fiber-orientation, and find the best settings in case of carbon fiber reinforced plastic 3D printing. The study also considers the need of the tuning of different manufacturing parameters and the modification of certain parts of the 3D printer to adapt it to the new material configuration. Furthermore this study includes the effect of surface-treatment with acetone at the printed objects in order to improve the transverse mechanical properties of the final parts. To carry out the study, different test specimens will be manufactured according to different manufacturing configurations and the mechanical properties of the material will be characterized by means of different standard tests. In my study to reach the desired quality I will print specimens with several parameters and investigate the effect of the settings to obtain the best setting for the best results. After I reached the proper settings in printing of both materials I printed more than 40 specimens in 3 directions to investigate the effect of the printing direction. Independently from the thickness of the layers the surface of the printed object never will be perfectly smooth. To reach the smooth surface to use acetone vapor as a surface treatment is a feasible way. In my study I would like to examine the effect of acetone, the necessary time for the treatment. After I prepare all of the specimens I can them with a tensile test machine. With this experiment I will be able to obtain the following mechanical properties: tensile stress, Young’s modulus, Yield strength and Poisson ratio