A volumetric resin printer now costs about $1,600 in parts, and you build it yourself. UC Berkeley has publicly released OpenCAL, an open-source computed axial lithography (CAL) machine. It forms a complete part inside a rotating vial of resin, with no layers. The project's reference print, a replica of Rodin's The Thinker, takes about 90 seconds. The hardware designs, software, firmware and a supported resin are all available now. The resin is made by Formlabs and sold in the US by Prusa Research.
The technique is not new. What's new is that anyone can now build one. The full package is out under a defined license, with a bill of materials you can source and resin you can order today. Here is what you are actually getting.
From a Science Paper to a Parts List
CAL is not new. The technique was invented in 2017 in Hayden Taylor's lab at Berkeley, working with Lawrence Livermore National Laboratory, and the work was published in Science in 2019. What is new is how easy it now is to get hold of one. According to 3D Printing Industry, the OpenCAL effort was led by Taylor Waddell and drew on more than 40 contributors over two years.
The accompanying arXiv paper describes the goal directly. The authors call OpenCAL a low-cost platform for CAL printing and post-processing, built from commercial off-the-shelf components and standard rapid-prototyping tools. It is aimed at academic makerspaces and education, and the paper describes "community engagement pathways" meant to keep development going beyond the original lab.
What's in the Box (That You Fill Yourself)
None of the V2 hardware is exotic. Per 3D Printing Industry, the build uses:
- A consumer LED projector as the light engine
- A Raspberry Pi 5 for control
- A stepper-driven mount that rotates the resin vial
- An aluminum extrusion frame
- Laser-cut acrylic panels
- Printed parts in PETG, PLA and TPU
Expect five to six hours of assembly. Anyone who has built a kit FDM printer or a large Voron-style project will know the skills involved: extrusion, fasteners, printed brackets and a single-board computer. The unfamiliar part is the optics and the way the machine works.
A conventional resin printer cures one thin slice at a time against a build plate. CAL works differently. It rotates a vial of resin while a projector shines a computed sequence of light patterns into it. The light dose adds up across the whole volume, and the target geometry solidifies all at once. That is why a full part can form in about a minute and a half. It also means there are no layer lines and no support structures.
The arXiv paper says the platform incorporates Optical Scattering Tomography, a way of observing the print volume while the part forms. Post-processing is part of the open design too. The paper describes solvent removal of uncured resin and a centrifugal cleaning module for enhanced material recovery. That second piece is worth noting, because the project includes its own answer to cleanup rather than leaving it to the builder.
Software: Tomo and VAMToolbox
Print preparation runs through Tomo, a free Windows application built on VAMToolbox. VAMToolbox is an open-source Python toolbox for volumetric additive manufacturing, and it handles the tomographic computation of turning a 3D model into the projection sequence. Tomo puts a desktop front end on it. The machine's software and firmware are published on GitHub.
Mac and Linux users should note that the source describes Tomo only as a Windows application. Because VAMToolbox is open Python, the underlying computation is not tied to Windows, but nothing in the release material promises a cross-platform front end.
Resin, Licensing and Cost
Volumetric printing depends heavily on its chemistry. The resin has to respond predictably to the accumulated light dose, and according to 3D Printing Industry, resin had been one of the main obstacles for home-built volumetric printers, since it previously had to be mixed by hand from laboratory chemicals. OpenCAL Resin is UDMA-based and manufactured by Formlabs. In the US, Prusa Research sells it through Printed Solid at $119.99 per 1-liter bottle with free shipping.
The hardware is released under the Prusa Open Community License, OCL 1.1. Builders should read its terms before planning anything commercial, instead of assuming permissive open-source rules apply. The software and firmware are distributed separately through GitHub. A Printables design contest built around OpenCAL is also planned, which suggests the project expects community upgrades and accessories, not just faithful clones.
The budget breaks down like this: roughly $1,600 in parts, about $120 per liter of resin, five to six hours of assembly, and a Windows PC for slicing. Before this release, CAL had lived in a handful of research labs for almost a decade, in the words of the project lead.
What It Means for Makers
Be clear about what OpenCAL is. The sources describe a research and education platform aimed at academic makerspaces, not a replacement for an MSLA printer on your bench. A reference part that prints in 90 seconds says a lot about the method's speed. It says nothing about how the machine handles your own parts or how much tuning a new build needs before it produces clean results. The only size guidance in the release material is a typical print time of one to two minutes for an inch-scale part, with no stated build volume or resolution, so anyone budgeting for a build should go into it as an experimenter.
For the right builder, though, this release matters. University makerspaces, school fab labs, hackerspaces and individuals who like opening up how a process works can now own a layerless printer, study it, modify it and share their changes under a defined license. They also get a commercially made, supported resin, so they don't have to work out a chemistry recipe from journal papers. The centrifugal cleaning module and the tomography integration show the project thought about the whole workflow, not only the printing step.
There is a broader point too. Desktop FDM became mainstream when open hardware reduced a lab technique to a parts list and a community picked it up. OpenCAL is a deliberate attempt at the same thing for volumetric printing: a published BOM, a license, a resin supply chain through an established maker retailer and a design contest to get people involved. Whether it catches on will depend on what the first few hundred builders manage to print.
