One-Vat Multimaterial 3D Printing: The Devil is in the Details

Nature combines different materials in a single structure to achieve functions that no single material could accomplish alone, an approach that inspires efforts to build synthetic systems with precisely tailored properties. Vat photopolymerization (VPP) enables fast, high-resolution 3D printing, but most printed parts still use only one material. This Outlook highlights emerging strategies for single-vat multimaterial VPP, where light selectively activates different chemical reactions to build complex structures with multiple materials. Key advances will depend on expanding resin chemistry beyond standard acrylates, improving reaction selectivity, and using grayscale and multiwavelength light control to define where and how materials form. Standardized mechanical, thermal, and interface testing methods are essential for ensuring reliable results. With advances in chemistry, optics, and data-driven design, multimaterial VPP could unlock transformative applications in medicine, manufacturing, and aerospace.