A hollow light-weight, low-cost, and high-performance 3D Luneburg lens structure using partially-metalized thin film, string, threads, fiber or wire base metamaterial to implement the continuously varying relative permittivity profile, characteristic of Luneburg lens structures, is disclosed. The hollow light-weight lens structure is based on the effective medium approach and may be implemented by a number of means. Further, most of the volume of the lens structure is free-space, thus the weight of the lens is significantly less than conventional 3D Luneburg lens structures of the same dimensions.