The present project focuses on Fused Filament Fabrication (FFF) technique which currently is one of the most important Additive Manufacturing technologies (AM). Nowadays additive manufacturing or 3D printing is one of the most emerging technologies which are coming to the market with a great impact, due to its industrial rapid prototyping technique (RP) innovation and its growing evolution within industrial area, where it has been established as a facilitator of mass customization of end-products. In this way, AM technology can be used for new purposes and finally enters the stage of end-product manufacturing. Several AM procedures have evolved to carry out every requirement of the different industries thereby it allows to manufacture end use products that can work at equivalent conditions as the manufactured using traditional techniques. Nevertheless, being a relatively recent means of manufacture, there is a certain lack of knowledge on how to carry out, in a satisfactory manner, the design process to obtain the desired properties in the manufactures object. The main difficulty in this process is not knowing clearly what influence the different manufacturing parameters to be found in this type of technology will have on the mechanical behaviour at the end-product. Having said that, this work has centred on understanding the effect that these 5 factors (nozzle diameter, layer height, fill density, speed and orientation) have on the mechanical behaviour at pieces manufactured by FFF submitted to traction effort, with the aim of showing what repercussion this will have on the final performance of the piece. To carry out this task, we drew up an experimental design (DOE) based on Taguchi’s statistical method, which permitted us to evaluate separately each factor and determine the inter-action between them, obtaining some relevant results with a minimum number of samples, due to its robustness. Later, we had recourse to a variance analysis (ANOVA) with the intention of confirming which manufacturing parameters have a real influence on the mechanical behaviour of the samples. The mechanical properties studied are Young Module, 0.2% Offset Yield Strength, Ultimate Tensile Strength, Maximum Elongation, Resilience Module and Tenacity Module.