Researchers at the University of California, Berkeley, released OpenCAL, a build-it-yourself volumetric 3D printer based on Computed Axial Lithography, along with a dedicated photopolymer manufactured by Formlabs and sold by Prusa Research. The printer forms an entire object at once inside a rotating vial of resin, typically in one to two minutes. Every drawing, line of code and resin recipe is public.

Computed Axial Lithography, or CAL, was invented in 2017 in Professor Hayden Taylor’s lab in Berkeley’s Department of Mechanical Engineering, in collaboration with scientists at Lawrence Livermore National Laboratory, and was first published in Science in 2019. For almost a decade, the process stayed inside a handful of research labs. OpenCAL packages it into a low-cost printer, free software, and a commercially available resin so that researchers, educators, and makers can build, use, and improve volumetric 3D printing. Taylor Waddell led the project, which took two years and more than 40 contributors, most of them Berkeley undergraduate and graduate students.

A CAL printer does not build parts layer by layer. A projector beams a rapidly changing sequence of computed light patterns into a rotating vial of photosensitive resin, and the resin solidifies wherever the accumulated light dose crosses the curing threshold. The whole part forms at once, with no layers, no support structures and no moving print head. The underlying math works like a CT scan in reverse: the software computes the projections needed to reconstruct a physical object out of light, where a scanner would reconstruct an image from X-ray projections. The reference part in the OpenCAL paper, a replica of Rodin’s Thinker, formed in 90 seconds. Taylor’s group has since adapted CAL for bioprinting and glass parts. Through the SpaceCAL program it flew CAL printers on NASA-supported suborbital flights and demonstrated the first autonomous volumetric print-and-post-process workflow in microgravity.

OpenCAL V2 is built around a consumer LED projector, a Raspberry Pi 5 and a stepper-driven vial mount. These sit in an aluminum extrusion frame with laser-cut acrylic panels and 3D printed PETG, PLA and TPU parts, small enough to carry in a camera case. The bill of materials comes to about $1,638 (June 2026 pricing), and once the parts are printed, one person can assemble the machine in five to six hours. Print preparation runs on Tomo, a free Windows application that turns an STL file into a print sequence without any coding. Tomo is built on VAMToolbox, an open-source Python library that solves the tomographic optimization at the core of the process. The printer runs open firmware and plays print files from a USB drive, and the documentation includes washing and curing procedures for post-processing.

“CAL has lived in a handful of research labs for almost a decade,” said Taylor Waddell. “Now almost anyone can be a part of this exciting research field, and actually make a meaningful difference and improve the technology through their contributions.”

Prusa and Formlabs jump in

Until now, anyone building a volumetric printer at home had to mix the resin by hand from laboratory chemicals, which made it one of the main obstacles. Formlabs, the Somerville, Massachusetts manufacturer of the Form series of professional resin 3D printers, now produces the Berkeley-developed UDMA-based formulation at production scale as OpenCAL Resin, in 1 L bottles. Formlabs has committed to further production runs as demand grows, and the recipe remains published for labs that prefer to mix their own.

Prusa Research, founded in Prague in 2012 by Josef Průša and rooted in the open-source RepRap project, sells the resin in the United States for $119.99 per bottle through Printed Solid, its US online store. It also hosts every OpenCAL printable part on its Printables model community, and the prototype parts were printed on a Prusa CORE One. The hardware is released under Prusa’s Open Community License (OCL 1.1), which guarantees the right to build, modify, repair and share the design, and the software is on GitHub. A Printables design contest for OpenCAL will follow the launch.

“OpenCAL is the kind of project that shows where 3D printing could be heading next, built by an extremely enthusiastic community and our friends at Berkeley,” said Rudolf Krcmar of Prusa Research. “Releasing it under the Open Community License means anyone can build, improve and share it, and we want to see OpenCAL printers popping up all over the world, because the faster it spreads, the faster this technology evolves.”

Both partners helped bring earlier 3D printing technologies to the desktop. Prusa grew out of the RepRap movement that put filament printers on hobbyist workbenches, and Formlabs moved stereolithography out of the service bureau and into offices and labs.

Open beyond Berkeley

Before the public release, Berkeley ran a pilot program in which universities, national laboratories and makerspaces built the printer from a draft guide and mixed the resin themselves, and their fixes went back into the documentation. OpenCAL machines are now running or under construction at MIT, Purdue University, Lawrence Livermore National Laboratory, the National Institute of Standards and Technology (NIST), and universities across North America, Europe and Asia, where several schools use them for classroom and capstone projects.

Hobbyists on the project’s Discord server, which has more than 2,200 members, have already printed parts on home-built machines. In February 2027, Berkeley will host a one-day OpenCAL build workshop at VAM27@Berkeley, its annual volumetric manufacturing symposium.