Terahertz radiation sources are currently one of the most widely used non-ionizing illumination mechanisms for security applications and also find increasing utilization in quality control of commercial products. Presently, a majority of these applications rely on scanning rather than direct imaging and implicitly suffer from temporal latency due to post processing. The monetary and temporal cost associated with procuring commercially manufactured optics that are suitable for imaging leads to fundamental limitations in the ability to rapidly develop application-specific imaging modalities using terahertz sources. Herein, we show a novel method for the rapid prototyping of metallic coated poly-methacrylate parabolic reflectors fabricated by stereolithographic 3D printing. Images comparing the performance of a commercially available off-axis parabolic reflector to our metalized poly-methacrylate prototype, which was designed to be identical to the commercially available mirror, are subsequently presented. The images show that at 530 GHz it is possible to produce a metalized poly-methacrylate off-axis paraboloid whose spatial beam profile is nearly identical to that of a commercially available equivalent.