The Moon serves as a stepping stone for humanity’s space colonization. Due to high transportation costs, utilizing lunar resources is considered essential for further development in space applications. Lunar regolith and its simulants exhibit a wide range of particle size distributions (PSDs). Simulants prepared under terrestrial conditions retain moisture, requiring pre-drying. Within this work, the influence of these characteristics on the melting process similar to a powder bed fusion process has been investigated. Simulant powders with different PSDs (particle sizes ≤ 1000 µm) and drying states (undried, 300 °C and 800 °C for 4 h) were processed in a vacuum chamber and the fabricated specimens profoundly analyzed. The results show an increase in specimen mass with larger particles and higher drying temperatures. No correlation of the PSD and drying temperature on the porosity was observed. Processing of undried simulants caused the formation of discontinuous melt tracks and a significant chamber pressure increase.