The present study is aimed to evaluate the independent effects of Fused Deposition Modeling (FDM) processing parameters on the mechanical characteristics and dimensional accuracy repeatability of FDM parts using an experimental approach. The study used various types of materials, including Acrylonitrile Butadiene Styrene (ABS), Poly lactic acid (PLA), and Polyethylene terephthalate glycol (PETG), and considered parameters such as layer height, infill density, and infill pattern. The output response parameters were tensile strength, dimensional accuracy, and surface roughness. To evaluate these parameters, a variety of tests were performed, including dimensional accuracy tests using Vernier Callipers, surface roughness tests using a surface roughness tester, and tensile tests using a universal testing machine (UTM). The results of the tests showed that ABS has the highest dimensional accuracy, whereas PETG has the lowest dimensional accuracy at 2%. The surface roughness values showed that ABS had the lowest Ra value of 1.852 microns, while PLA had the highest Ra value of 2.92 microns for width and PLA had the lowest Ra value of 4.837 microns, while PETG had the highest Ra value of 8.576 microns for thickness. In terms of mechanical properties, ABS had the highest tensile strength (26.08 MPa) and modulus of elasticity (475.04 MPa) at 0.2 mm layer thickness and 100% infill density among the three materials, while PETG had the lowest tensile strength (15.24 MPa) and modulus of elasticity (219.28 MPa) at 0.3 mm layer thickness and 40% infill density with grid infill pattern. Furthermore, multi-criteria decision-making techniques are employed to evaluate the optimal process parameters and a comparative analysis is made using two popular MCDM techniques, i.e., Additive Ratio Assessment (ARAS) and Complex Proportional Assessment (COPRAS). The results of this study can assist in the development of FDM processing parameters that produce FDM parts with desired mechanical properties, dimensional accuracy, and surface roughness.