With the latest developments in 3D printing technologies and decreases in their costs, these prototyping methods are now being used extensively in many applications for fast, low-cost, and precise prototyping. In this work, 3D printing technology had been used for prototyping of nonuniform substrate dielectric lens antennas. For this, two study cases had been taken into consideration: (a) design of a dielectric lens antenna with 25 nonuniform height dielectric pillars with constant dielectric value, and (b) design of a dielectric lens antenna with 25 pillars of nonuniform dielectric constant value but equal height. Both of the designs, first, were modeled in 3D EM simulation environments and then were prototyped via 3D printing technology. Both the simulations and measured results of the prototyped antennas were compared and found that they were agreeable. Both of the antenna designs achieved a measured gain level of almost 17.4 dBi at 10 GHz, with a return loss of less than -10 dB. Thus, as it can be observed from the experimental results, the proposed 3D printing-based manufacturing process is an efficient solution for the realization of high-performance nonuniform substrate dielectric lens antennas that are either difficult or impractical with conventional prototyping methods.