Self-activating resins for the straightforward electroless metallization of 3D printed parts

A self-activating photocurable resin system is proposed as a cost-effective route for the direct electroless metallization of 3D printed components. The strategy relies on the incorporation of inexpensive metallic precursors, namely NiCl 2 and CuSO 4 , into a commercial digital light processing (DLP) resin, enabling the in situ formation of catalytic sites after a single chemical reduction step. This approach removes the need for conventional multi-step surface activation and the use of noble metals such as palladium. The rheological and photopolymerization behavior of the composite resins demonstrates that all formulations remain compatible with DLP printing, with the embedded salts significantly affecting viscosity, curing depth and mechanical properties of the resulting photopolymerized materials. The printed parts are reduced in aqueous environment, resulting in partial dissolution and conversion of the precursors into metallic nuclei that can initiate electroless deposition of NiP and Cu. The obtained metallic coatings exhibit uniform morphology, compact structure and strong adhesion to the polymer substrate, as confirmed by SEM/EDS and XRD. Moreover, the metallized substrates enable the sequential electroplating of multiple metallic layers using electrolytic deposition, producing continuous and adherent multilayer architectures. The versatility of the proposed method is further expanded through multimaterial DLP printing, which allows selective metallization by combining clear and self-activating regions within a single object. Metallization occurrs exclusively in the catalytically active areas following reduction. Overall, this study introduces a simple and scalable metallization route for polymer-based additive manufacturing, reducing cost and process complexity while maintaining high coating quality. The proposed self-activating resins provide a sustainable pathway toward functional metallic architectures, electronic interconnects and decorative finishes produced directly via DLP 3D printing.