Faced with the proliferation of plastic waste (LDPE), the overexploitation of Sanaga sand, and the under-utilization of coconut husks in Cameroon, this study developed and characterized an innovative ternary composite. The aim was to establish an artisanal manufacturing process and optimize the proportions of Low-Density Polyethylene (LDPE) waste, Sanaga sand, and coconut husk powder for sustainable construction. The process, inspired by ecological paving, tested nine formulations (LDPE 20-40%, sand/coconut 0-10%). Samples were characterized for their apparent density, water absorption rate, and mechanical properties (bending). Results showed a decrease in density with LDPE and coir powder. Water absorption remained very low (max. 0.640%), guaranteeing excellent durability in damp conditions. Although maximum flexural strength was lower than for thermo-compressed composites (probably due to the absence of pressure compaction in the artisanal method), the incorporation of coir conferred a certain ductility. Some formulations (F0/40, F5/20) are potentially usable for T4/T5 or T5 type pavers, and indoor flooring (P2). Future optimization will include pressure compaction and improvement of the LDPE/coconut interface to enhance performance. This work contributes to sustainable waste management and the promotion of environmentally-friendly building materials.