Prusa Research released the first public preview of PrusaSlicer 3.0 on September 1, 2026. The date is not an accident: it is exactly 15 years after the first commit to Slic3r, the project PrusaSlicer was originally forked from, back on September 1, 2011. Josef Prusa calls this the biggest upgrade in the software’s history, and after going through what actually shipped, that is not just launch-day talk. A large part of the application, starting with the entire user interface, was rewritten from scratch.
This has been coming for a while. When Prusa refreshed its XL+, CORE One+ and CORE One L+ printers in August, the announcement mentioned a PrusaSlicer 3.0 alpha was a few weeks away. That preview is out now, and it goes further than a routine version bump.
One project can hold several printers
PrusaSlicer 2.9.0 added multiple beds, but the feature stayed minimal, capped at nine beds with no real independence between them. In 3.0, each bed is a full part of the project with its own configuration, so a single project can mix an MK4S bed and an XL bed side by side, each with its own profile, and the nine-bed limit is gone. Slicing now processes the beds in parallel instead of one after another.
You do not need a printer farm to get something out of this. Even with a single machine, separate beds let you group different materials or settings inside one file instead of juggling multiple projects. PrusaSlicer can also keep several projects open at once, each in its own tab with its own selections and dialogs, and it now backs up open projects locally on a rolling basis, so a crash does not cost you the session.
A profile system built for multi-tool printers
The old profile format could not really describe a printer like the XL, where each tool can carry a different nozzle diameter. Doing that meant keeping three separate printer profiles and switching between them by hand. In PrusaSlicer 3.0, picking a nozzle is just choosing a tool from a list, and a single project can assign different print profiles to different tools directly. The profile format itself moved from .ini to .yaml. Old projects are not stranded: a 3MF saved in PrusaSlicer 2.x still loads its geometry and settings correctly in 3.0. Going the other way loses the settings, and PrusaSlicer 2.9.1 and later will warn you when that happens.
Plugins, sandboxed from the start
PrusaSlicer has always been open source, which is exactly how OrcaSlicer, SuperSlicer and Bambu Studio came to exist as forks in the first place. Forking an entire slicer for one feature is a lot of work, though, and most forks stall after a while. Version 3.0 adds a plugin system so the community can extend PrusaSlicer without forking it. The first two examples ship with this release: parametric Flow tower and Temperature tower calibration prints, built as Lua plugins that generate a ready project from a few typed-in parameters.
What stands out is the security model. Plugins run in a sandbox with no general access to disk, no access to data outside the loaded project, and no network access at all, and anything submitted to the future plugin marketplace goes through a review process first. We wrote back in August about OrcaSlicer shipping its own Python plugin system, whose security layer its own developers described as unfinished. Prusa is starting from the opposite end: sandboxing first, marketplace later.
A real offline mode
PrusaSlicer 3.0 lets you turn off every online service, Connect, Printables, even profile update checks, before any network call happens. In full offline mode the networking libraries are not loaded at all, so there are no background connections and nothing for a firewall to flag. That matters if you run PrusaSlicer on an airgapped or restricted machine.
Don’t replace your daily driver yet
This is an early preview, not a production build, and Prusa says outright that it is not feature complete against 2.9.6. Some ported features are waiting for the 3.1 release. The upside is that you do not have to choose between old and new: PrusaSlicer 3.0 stores its profiles in a separate directory and installs side by side with 2.x without conflicts, so you can try the new interface without touching the slicer you actually rely on to print. PrusaSlicer 3.x stays under the AGPLv3 license, the same as 2.x, Slic3r PE and the original Slic3r before it.
The preview is a free download from prusa3d.com. Worth a look if you are curious where the software is headed, just not on the machine you need for a print tonight.
Source: PrusaSlicer 3.0 Preview, Built for the Future of 3D Printing, Prusa Research, September 1, 2026.