OpenCAL Brings Volumetric 3D Printing to the Desktop for $1,400

Standard desktop 3D printers fabricate objects layer by layer, which means long waits and visible layer lines. A new open-source project called OpenCAL takes a fundamentally different approach. It uses computed axial lithography to solidify entire geometries at once, producing fully formed objects in about 20 seconds.

How volumetric printing works

Traditional resin printers cure flat cross-sections onto a rising build plate. Filament printers extrude plastic line by line. Both methods stack hundreds of thin layers. OpenCAL skips the stacking entirely.

A glass cylinder filled with viscous resin spins inside the machine while a projector shines patterns of blue light through it from multiple angles. The light accumulates energy at specific coordinates inside the liquid, hardening the material only where the geometry should be solid. When the rotation finishes, the part is complete. There is no layer-by-layer slicing, no Z-axis movement, no overnight print.

Researcher Taylor Waddell demonstrated the system on YouTube, producing a miniature space shuttle in 20 seconds. The part came out of the resin with no layer lines and no mechanical weak points between layers. Post-processing is familiar to anyone who has used a resin printer: a quick isopropyl alcohol wash, then an ultraviolet cure under sunlight or a UV lamp.

Built from off-the-shelf parts

The OpenCAL design is deliberately accessible. A Raspberry Pi controls the system, driving an LCD and streaming MP4 video files directly to the projector. No complex G-code translation is needed. The machine locks alignment with a custom three-axis screw adjustment mount to keep the light centered in the cylinder. Everything else is basic hardware.

The firmware is available on GitHub. Step-by-step build documentation is free online. The estimated material cost is around $1,400, with the laser projector accounting for most of that expense. That is not cheap, but it is far less than the custom equipment volumetric printing previously required.

The project partnered with Formlabs and MatterHackers to distribute pre-mixed photopolymer resins at cost. That arrangement addresses safety concerns. Uncured resin can cause skin irritation, and bulk vials left in direct sunlight can generate runaway exothermic heat. Users still need to handle materials carefully, but the partnership removes the guesswork from sourcing compatible photopolymers.

Why this matters

Volumetric printing has been confined to university labs because the equipment was custom, massive and expensive. OpenCAL collapses that barrier. The finished machine fits in standard checked luggage, which means it is portable in a way no consumer resin printer is.

There are limits. The build volume is small. The resin palette is narrower than what SLA printers offer. And $1,400 is still a significant investment for hobbyists. But for anyone frustrated by overnight prints and layer lines, this is the most interesting development in desktop fabrication this year.

The files are free. The documentation is free. The barrier to entry is lower than it has ever been for a printing technology this different. Whether OpenCAL becomes a mainstream platform or a niche curiosity, it has already proven that volumetric fabrication does not need a research budget to work.