Engineers have developed a low-cost, open-source 3D printer that fabricates ultra-flexible soft robots upside down, allowing them to walk off the print bed as soon as printing is complete, no post-processing required.
Study: A standardized platform for translational advances in fluidic soft systems. Image Credit: Maks Gepner
In a new study published in Device, researchers introduced the Flex Printer, a novel 3D printing platform built to streamline soft robot production. By flipping the conventional printing process on its head—literally—the system can produce fully soft, fluidically controlled robots in a single, continuous print.
The approach significantly lowers the cost and complexity of fabrication, aiming to open up soft robotics to a broader range of users and applications, from healthcare and wearable tech to manufacturing and human-machine interfaces.
Tackling the Bottlenecks in Soft Robotics
Soft robots have long held promise in fields where flexibility, adaptability, and safety are crucial. But despite their potential, progress toward real-world deployment has been slowed by practical limitations. One of the biggest challenges is fabrication.
Conventional methods for producing soft robots often involve expensive printers, specialized materials, and manual assembly steps that limit reproducibility and scalability. Even the most advanced systems tend to rely on rigid components or external support structures, undermining the vision of truly soft, integrated machines.
That’s the problem the Flex Printer sets out to solve. It offers a standardized, open-source solution built for reliability and affordability, capable of printing complex, fully soft robots in one go.
Engineering the Flex Printer: What Makes It Work
Central to the Flex Printer’s capabilities are a series of smart hardware upgrades. Switching from the common 1.75 mm filament to a thicker 2.85 mm version was a key move. This change increases resistance to buckling by a factor of seven, allowing smooth extrusion of ultra-flexible materials and dramatically reducing the risk of jams.
To support high-speed, high-precision printing, the platform uses a CoreXY motion system and Klipper firmware, with features like resonance compensation and a rigid Voron0-inspired frame. These design choices allow travel speeds of up to 500 mm/second and accelerations of 10,000 mm2/second—fast enough to minimize filament ooze, eliminate the need for retraction, and simplify print tuning for users.
Material compatibility was also carefully considered. Thermoplastic polyurethane (TPU) adheres reliably to a polyetherimide (PEI) print surface, meaning no heated bed is required, even when printing upside down. Combined with a direct-drive Orbiter F2.85 extruder, copper-plated nozzles, a titanium heat break, and active cooling from high-powered fans, the setup enables complex, support-free prints with minimal maintenance.
Why Upside-Down Printing Changes Everything
Fused deposition modeling (FDM) traditionally struggles with soft materials, especially when bridging gaps or building tall, thin structures. Gravity works against you, causing sagging and poor layer adhesion that can compromise the print.
By flipping the print orientation, the Flex Printer turns this problem into an advantage. Printing upside down counteracts gravitational sag, allowing unsupported strands to fuse cleanly. This is especially valuable for creating wide, leak-tight bridges essential in soft robots with internal fluid channels. Vertical membranes, which would normally collapse under their own weight, are now kept taut and stable under tension.
Adding to this is the introduction of “aero supports”—thin, non-fusing vertical columns that support delicate structures during the build. These are lightweight, easy to remove, and can even be designed to function as part of the robot, such as pressure-sensitive release membranes.
Proof in Motion: A Walking Soft Robot
To demonstrate what the system can do, the research team printed a soft robot embedded with a CMOS-based pneumatic ring oscillator. Thanks to the upside-down printing method, integrated aero supports, and optimized design, the robot was able to walk straight off the print bed as soon as fabrication ended. No assembly, no calibration—just a working robot activated by air pressure.
This demonstration marks a notable step forward. It shows that soft robotic systems, once seen as complex research tools, can now be created reliably, affordably, and autonomously.
Building the Future of Soft Robotics
The Flex Printer addresses critical hurdles in soft robotics manufacturing by combining affordability, accessibility, and precision. Its upside-down printing approach, coupled with thoughtful hardware design, allows users to print fully functional, flexible robots with fluidic logic in a single step—no cleanup or post-processing needed.
Features like wide, leak-tight bridges, tensile-stabilized vertical membranes, and multifunctional aero supports pave the way for high-performance soft systems to become far more attainable. And with its open-source design, the platform invites experimentation and adaptation across disciplines.
As soft robotics moves beyond the lab and into everyday applications, tools like the Flex Printer could be key to accelerating that shift, making it easier for developers, educators, and engineers to bring soft machines to life.
Journal Reference
Gepner, M., Mack, J., & Stokes, A. A. (2025). A standardized platform for translational advances in fluidic soft systems. Device, 100800–100800. DOI: 10.1016/j.device.2025.100800. http://dx.doi.org/10.1016/j.device.2025.100800
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