In this study, we apply the adjoint method to design Gradient Index (GRIN) Lens, optimizing the dielectric constant at each point to maximize specific goal functions. Our approach utilizes a full-wave 2D FFT solver to derive the solution quickly-within seconds-and the total optimization process takes only minutes. The designs are then realized using different 3D printing techniques, allowing for precise and efficient manufacturing. This method results in a distinctive ring-shaped lens design that is lightweight (163 grams) and achieves an aperture efficiency of 57%.