  Three-dimensional (3D) printing has emerged as a powerful tool for material,
food, and life science research and development, where the technology
democratization necessitates the advancement of open-source platforms. Herein,
we developed a hackable, multi-functional, and modular extrusion 3D printer for
soft materials, nicknamed Printer.HM. Multi-printhead modules are established
based on a robotic arm for heterogeneous construct creation, where ink
printability can be tuned by accessories such as heating and UV modules.
Software associated with Printer.HM were designed to accept geometry inputs
including computer-aided design models, coordinates, equations, and pictures,
to create prints of distinct characteristics. Printer.HM could further perform
versatile operations, such as liquid dispensing, non-planar printing, and
pick-and-place of meso-objects. By mix-and-match software and hardware
settings, Printer.HM demonstrated printing of pH-responsive soft actuators,
plant-based functional hydrogels, and organ macro-anatomical models.
Integrating affordability and open design, we envisage the Printer.HM concept
to widen open innovations for soft, biological, and sustainable material
architectures.
