Optimization is one of the most important issues in design and manufacturing. Topology optimization (TO) is one of the most useful methods of optimization which tries to achieve not only the minimum volume but also the desired characteristics such as mechanical properties. Material is disturbed throughout the design region by TO. The output of TO includes a re-designed model with complex structure, and intermediate densities (densities between zero and one) that are spread throughout the model. Therefore, the optimized model contains elements with intermediate densities. Because it is not possible to manufacture parts with intermediate densities, the elements whose densities are smaller than a particular value are replaced by holes with proper size. One the other hand, these models usually have complex geometries that cannot be manufactured by the traditional manufacturing processes. Additive manufacturing (AM) processes enable the production of parts with complex geometries, multi-materials as well as individualized mass production. Another sustainable benefit of AM is the ability to produce optimized geometries with near-perfect strength-to-weight ratios. Weight plays a crucial role in many parts such as those used in vehicle and aircraft industries. Since AM methods necessitate applying own dedicated design rules, Current topology optimization techniques do not work well for such kind of processes. The purpose of this study is to determine the design rules of these processes use the advantages of them and achieve a part whose geometry is as close as possible to output of TO. The minimum strain energy of the model was chosen as the objective function of TO, and the effect of different shape of holes were investigated. The priority of each shape were then determined based on its global strain energy. After having optimized the model, the density of each element was used to calculate the shape and the size of a proper hole considering the manufacturing process limitations. Among AM processes FDM (Fused Deposition Modeling) was selected for fabricating the optimized models. In order to evaluate the capability of the FDM machine, FDM Rapman3.2, for producing the minimum wall thickness as well as the smallest pore size, a number of benchmarks were designed and fabricated. Two MBB beam were optimized and redesigned with the proper shape and size of holes considering the FDM limitations. MBB (Messerschmitt-B?lkow-Blohm) beams were fabricated and after applying experimental test the result compares with finite element analysis. This methodology was applied in a gear and re-modeled gear with lower weight was obtained in the way that its functional capability was remained. Finally, one tooth of the gear was fabricated by the FDM machine to determine the ability of producing re-modeled gear. Keyword : topology optimization, additive manufacturing, FDM, manufacturing limitations.