In 2014, NASA, in partnership with Made In Space, Inc., launched the first 3D printer to the International Space Station. Results of the first phase of operations for this mission demonstrated use of the fused filament fabrication (FFF) process for 3D printing in a microgravity environment. Previously published results indicated differences in density and mechanical properties of specimens printed in microgravity and those manufactured with the printer prior to its launch to ISS. Based on extensive analyses, these differences were hypothesized to be a result of subtle changes in manufacturing process settings rather than a microgravity influence on the FFF process. Phase II operations provided an opportunity to produce additional specimens in microgravity, evaluate the impact of changes in the extruder standoff distance, and ultimate provide a more rigorous assessment of microgravity effects through control of manufacturing process settings. Based on phase II results and a holistic consideration of phase I and phase II flight specimens, no engineering-significant microgravity effects on the process are noted. Results of accompanying material modeling efforts, which simulate the FFF process under a variety of conditions (including microgravity), are also presented. No significant microgravity effects on material outcomes are noted in the physics-based model of the FFF process. The 3D printing in zero G technology demonstration mission represents the first instance of off-world manufacturing. It represents the first step toward transforming logistics for long duration space exploration and is also an important crew safety enhancement for extended space missions where cargo resupply is not readily available. This paper presents the holistic results of phase I and II on-orbit operations and also includes material modeling efforts.