A one-step volumetric biofabrication platform for complex hydrogel-based hollow biomaterials.

Rotational molding (RM) is a widely used industrial process for producing hollow polymeric structures, yet it remains largely unexplored for biomaterials fabrication. Here, a low-cost 3D-printed biofabrication platform is introduced that adapts the general concept of RM to generate tunable hollow constructs with high structural fidelity. Using uniaxial RM, tubular-like hydrogels with precisely controlled diameter and wall thickness are generated by crosslinking light-responsive natural-based polymers, such as modified proteins and polysaccharides, under mild, cell-compatible conditions. The process yields reproductible geometries and well-defined walls while maintaining long-term cell viability. Furthermore, extending the system to biaxial RM allows the rapid, one-step fabrication of more complex hollow 3D architectures. By integrating established RM principles with biocompatible photochemistry, this accessible platform provides a scalable and versatile route to engineer hollow hydrogel architectures using virtually any kind of hydrogel forming material, independent of their rheological properties or crosslinking conditions. These capabilities expand opportunities in tissue modeling, biohybrid living actuators, and regenerative medicine, positioning RM as a powerful strategy for the controlled design of functional hollow hydrogels.