Technological development and progress in various areas such as manufacturing and materials have resulted in various components becoming leaner, reducing material consumption, thus minimizing waste, and contributing to the environment. In addition, the manufacturing time of mechanical elements is reduced, reducing costs. By using the finite element method, a lattice structure optimization was performed in an original model. Three lattices were applied in the optimized model. This method uses optimization algorithms to generate geometries with an optimal distribution of material, maximizing the strength and minimizing the weight of the component. From the lattices: regular cubic, double pyramid and double transversal pyramid a reduction between 52.63–60.53% of the mass was achieved with respect to the model with an infill of 100%. Experimental tests were performed on the 3D printed models to verify their mechanical strength compared to the spur gear model with the 100% filling. All models were subjected to the maximum torque and speed in the test bench, none of the spur gears showed any damage when inspected.