Designing an Open-Source Multi-vat Digital Light Processing Printer

Additive manufacturing has undergone rapid evolution in modalities that can recreate native human tissue architectures with high resolution. Among emerging approaches, digital light processing (DLP)-based printing enables the fabrication of intricate biomimetic architectures through the photopolymerization of polymer-based hydrogels. The recent emergence of multi-material printing further enhances this capability, enabling the complex spatial arrangement of heterogeneous cells and diverse bioink compositions. However, the widespread adoption of DLP printing remains constrained by the high cost, proprietary hardware, and limited customizability of commercially available systems. Here, we present an open-source multi-vat DLP printing platform developed through the integration and modification of two low-cost commercially available 3D printers. A dedicated Python-based graphical user interface was developed, providing user-defined control over critical printing parameters, including exposure time, layer height, printing sequence, and material switching. Comprehensive hardware documentation and a complete bill of materials (BOM) are provided to ensure reproducibility and accessibility across research laboratories. In addition to multi-material printing, the system enables spatial modulation of mechanical properties within a single bioink formulation through programmable light exposure and supports enhanced z-axis resolution through user-defined layer thickness control. The platform was validated through the fabrication of geometrically complex, multi-material, and mechanically heterogeneous constructs. Collectively, this work establishes an accessible and customizable DLP printing platform that enables advanced biofabrication and facilitates the engineering of compositionally and mechanically heterogeneous tissue-mimetic construct.