3D printing LDPE/lunar regolith simulant composite: manufacturing with in-situ resources on the moon

Additive manufacturing is essential for space missions, enabling on-demand production of components where resupply from Earth is limited. Fused deposition modeling (FDM) offers a promising route for repurposing plastic packaging waste into 3D printing feedstock. Low-density polyethylene (LDPE), commonly used in space packaging, can be combined with lunar regolith simulant to increase material availability for in-situ resource utilization (ISRU). However, the method of incorporating regolith into the polymer matrix affects filament quality and printability. Here, we compare single-screw and twin-screw extrusion techniques for producing LDPE/regolith composite filaments containing up to 30 wt% regolith. Both methods successfully produced filaments suitable for FDM, though single-screw extrusion required a second extrusion step above 10 wt% regolith. Filaments were evaluated for diameter consistency and printability, including the successful fabrication of NASA-designed parts. Regolith addition enhances print performance by improving overhang formation, gap bridging, and reducing warpage. Tensile testing shows increased stiffness without compromising strength up to 20 wt% regolith. These results demonstrate that LDPE and lunar regolith can be effectively processed into printable feedstock, supporting sustainable manufacturing strategies for lunar applications and advancing terrestrial plastic waste recycling.