Extrusion based additive manufacturing, also known as Fused Deposition Modelling (FDM), is an interesting method for the production of complex geometries with as high as possible degree of design freedom. One of the limitations of the production technology is the adhesion of the printed filaments both in x, y and z-direction. This will affect parameters such as density and mechanical characteristics. This paper focuses on the influence of material selection and rheology on the morphology and mechanical properties of the final printed parts. Therefore, parts of poly-lactic-acid (PLA), Acrylonitril Butadiene Styrene (ABS) and High Impact Polystyrene (HIPS) have been produced into adequate filaments, followed by 3D Printing via FDM technology. Polymers with different types of rheology were applied in order to quantify both the effect of the rheology and build strategy during the 3D Printing processing steps. Samples were subjected to extensive characterization. The influence of the processing parameters on density and morphology was investigated by using Scanning Electron Microscopy and density measurements. The observations from the fracture surfaces were discussed and compared with mechanical properties (tensile and impact).