Plastics industry is growing day by day; the new techniques generated by the fourth industrial revolution, such as additive manufacturing (AM) or better known as 3D printing, make the design and production of plastic products available to all. The aim of this research aims to explore the application of reverse engineering in improving the mechanical displacement in AM. The method used in this paper was the finite element analysis (FEM) applying it to different 3D printing parameters with a grid infill. Then the multiple line regression (MLR) was implemented to determine parameters relation. Finally, the simplex method to improve the parameters to decrease the mechanical displacement in AM. Reverse engineering process for parts that use 0.2 as shell wall and 25% of grid infill can have acceptable mechanical performance to be used in different applications.