As millimeter-wave imaging technology becomes more mature, several applications are emerging for which this technology may be useful. However, effectively predicting the nuances of millimeter-wave phenomenology on the usefulness for a given application remains a challenge. To this end, an accurate millimeter-wave scene simulator would have tremendous value in predicting imager requirements for a given application. Herein, we present a passive millimeter-wave scene simulator built on the open-source 3d modeling software Blender. We describe the changes made to the Blender rendering engine to make it suitable for this purpose, including physically accurate reflections at each material interface, volumetric absorption and scattering, and tracking of both s and p polarizations. In addition, we have incorporated a mmW material database and world model that emulates the effects of cold sky profiles for varying weather conditions and frequencies of operation. The images produced by this model have been validated against calibrated experimental imagery captured by a passive scanning millimeter-wave imager for maritime, desert, and standoff detection applications.