In this research; an armrest of an office chair is studied by Fused Deposition Modeling, while ensuring requirements of TS EN 1335 are met in each one of design, analysis, optimization and testing phase. The effect of two different optimization studies for the interior volume of the armchair model was investigated. In the first optimization study, an appropriate outer section thickness and cellular size change when the inner filling of the armrest shows a homogeneous distribution. In another optimization study, a regional density optimizations evaluated wherein regions having a high tension on the armrest model are defined with a homogeneous low density, relative to other regions with a fuller density. According to the finite element analysis results of the homogeneous density models with 50% occupancy; In armrest models with close weight, reductions in von-Mises stresses ranging from 29% to 36% have occurred for various load conditions. However, a suitable alternative that did not exceed the safe limit stress values established by reference to tensile and bending tests could not be obtained. In the regional density optimization study, the von-Mises stress value is obtained approximately 20% lower over four test loads than the best alternative with homogeneous density, and a suitable result is obtained according to the safe limit stress values with this model. This armrest model with the appropriate result has been produced and subjected to validation tests. As a result of the tests, it has been determined that the model fulfills the required requirements.