PrusaSlicer 2.9.2-rc1

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Summary

This is the first release candidate of PrusaSlicer 2.9.2. It mostly fixes bugs found in 2.9.1.

The release candidate uses the regular PrusaSlicer configuration folder.

Improvements with respect to 2.9.1

• When importing STEP files, the geometry is converted into triangulated mesh which PrusaSlicer internally works with. The triangulation is performed with some defined precision - higher precision results in higher memory requirements and slower slicing, but the triangulated mesh is closer to the geometry that the STEP described. Until now, PrusaSlicer used some hardcoded defaults. In this version, there is an extra dialog shown during STEP file import, where the required quality of the triangulation can be selected. Last used selection is kept and the dialog can be dismissed for good by the "Remember my choice" checkbox. However, there is an option in Preferences -> Other to start showing it again.

Bugs fixed with respect to 2.9.1

• Fixed a crash in the new SLA support points generator.
• Fixed freezing in the new SLA support points generator (possibly fixing #14281).
• Scarf seams were not generated at all in certain cases (#14278).
• Fixed two distinct cases of incorrect function of the sequential arrange / test feature, both resulting into extruder possibly hitting a previously printed object (#14298, #14304).
• Fixed a crash in the sequential arrange algorithm happening in rare cases when multiple instances were present.
• Fixed input data for sequential arrange XL and CORE ONE (#14354), improved precision for MK4S so the arrange is not too conservative.
• Fixed tolerance-related issue in sequential arrange test, sometimes causing rejection of valid object positioning.
• Fix a crash when loading invalid STL file (very old bug) (#14343)
• Fixed measurement of distance between parallel-aligned circles (#14360).
• Fixed inadvertent rejection of 3MFs containing only configuration and no geometry.

Translations

• Updated POT
• Updated CS, PL, DE, IT, ES, FR, JA dictionaries.

Linux build is now distributed through Flathub. Please see the respective page on our Prusa Knowledge Base for instructions.

PrusaSlicer 2.9.1

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Summary

This is the final release of PrusaSlicer 2.9.1. It is functionally equivalent to 2.9.1-rc2.

Please, read change logs of 2.9.1-alpha1, 2.9.1-beta1, 2.9.1-rc1 and 2.9.1-rc2 to see all changes with respect to 2.9.0. You can also check our blog article to get the summary.

When you first run the final build, it will search for all configurations produced by alpha or beta versions and offer to create a copy of the latest one.

Linux build is now distributed through Flathub. Please see the respective page on our Prusa Knowledge Base for instructions.

PrusaSlicer 2.9.1-rc2

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Summary

This is the second release candidate of PrusaSlicer 2.9.1. This release fixes two bugs found in 2.9.1-rc1.

The release candidate saves its profiles into regular PrusaSlicer configuration directory. When you first run it, it will search for all configurations produced by alpha or beta versions and offer to create a copy of the latest one.

Changes with respect to 2.9.1-rc1

• Test of sequential printability reported names of the colliding objects incorrectly in certain cases (the test itself was correct). #14238
• Fixed freezing of the new SLA support points generator in certain cases.
• In very rare cases, the new SLA support points generator was crashing. These cases are now detected and an error message is shown instead.

Linux build is now distributed through Flathub. Please see the respective page on our Prusa Knowledge Base for instructions.

PrusaSlicer 2.9.1-rc1

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Summary

This is the first release candidate of PrusaSlicer 2.9.1. This release is basically equivalent to 2.9.1-beta1.

The release candidate saves its profiles into regular PrusaSlicer configuration directory. When you first run it, it will search for all configurations produced by alpha or beta versions and offer to create a copy of the latest one.

Changes with respect to 2.9.1-beta1

• Linux Flatpak build uses a different runtime version to hopefully mitigate issues with some dedicated GPU cards. #13945

Localization

• Updated CS, PL, DE, IT, ES, FR, JA dictionaries.

Linux build is now distributed through Flathub. Please see the respective page on our Prusa Knowledge Base for instructions.

PrusaSlicer 2.9.1-beta1

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Summary

This is the first beta release of PrusaSlicer 2.9.1. This release introduces new algorithm for generation of SLA support point and couple of bugfixes.

To let you enjoy the beta without worries, the beta builds save their profiles into PrusaSlicer-beta directory, so you may use the beta side by side with the current release without ruining your production configuration.

New SLA support point generator

We are introducing a brand new SLA support spot generator, which replaces the existing solution and provides more precise and predictable support placement. The new algorithm better differentiates the areas requiring support – small, medium, and large islands, as well as overhangs – and adapts the support strategy accordingly.

• Small islands are supported by a single point placed at their center of mass.
• Medium islands use the Voronoi diagram to optimally place two or more supports.
• Large islands are divided into thin and thick sections, where supports are placed either along the central axis or around the perimeter for greater stability.
• For detected overhangs, the algorithm dynamically adjusts the support density based on Z height and overhang angle, minimizing unnecessary supports and ensuring even distribution.
  

The new algorithm is not randomized and it produces same results when given the same input repeatedly. In general, it is a great improvement over the old algorithm, which often failed in a spectacular manner even in seemingly very simple cases:

Additional changes make it easier to manage supports and enhance visual feedback:

• Support density can now be adjusted with a single slider – moving it instantly updates the preview, enabling smooth and quick fine-tuning.
• A new toggle for displaying the support structure allows users to hide or show the entire support construction for better model visibility.
• Manually added points are no longer ignored – when the user presses Automatic Support Generation, the algorithm considers them and adjusts the surrounding support density accordingly.
• Support types are color-coded, distinguishing islands, manual edits, and overhang supports.

Bugs fixed with respect to 2.9.1-alpha1

• CLI options export_sla and export_gcode were reintroduced after they were erroneously removed in 2.9.1-alpha1.
• When sending multiple beds to Connect, PrusaSlicer allowed characters in the filenames that Connect would refuse. This is now fixed and the names are refused immediately.
• Remove an extra 1.5s pause after toolchange on an XL printer. This pause has a meaning for MK4, but including it for the XL makes no sense and could lead to issues. #13987
• Fixed Compare presets dialog, which did not correctly filter presets when the user changed selection.
• The new option to propagate thumbnails from 3MF to the G-code when using CLI was rescaling the images incorrectly and they ended up stretched. Images are now cropped to prevent this from happening.
• Scarf seams are now suppressed on the first layer to prevent adhesion problems. #11621 (comment)
• Fix couple of links to the web manual pages.
• Disable scarf seams on thick bridges. This is beneficial for print quality and it could also cause scraping the print bed if such bridge was on the second layer. #14190
• Added sequential arrange data for HT90.
• Fix crash during interlocking calculation in specific cases. #14163
• SLA: Fixed object placement on the bed after using auto-orientation. It stayed partially under the bed.

Translations

• Updated POT
• Updated CS, PL, DE, IT, ES, FR, JA dictionaries

Linux build is now distributed through Flathub. Please see the respective page on our Prusa Knowledge Base for instructions.

PrusaSlicer 2.9.1-alpha1

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Summary

This is the first alpha release of PrusaSlicer 2.9.1. This release introduces new algorithm to detect collisions during sequential printing, multi-material interlocking, and many bugfixes - mostly of older bugs.

To let you enjoy the alpha without worries, the alpha builds save their profiles into PrusaSlicer-alpha directory, so you may use the alpha side by side with the current release without ruining your production configuration.

Arrange for sequential printing

We are introducing a completely new algorithm to detect collisions during sequential printing. But not only that by far. We have actually made a new arrange algorithm that automatically positions and orders objects in such a way that collisions are avoided. Using sequential printing thus becomes safer and very easy to setup.

Just to give some context, PrusaSlicer allows sequential printing of objects (Print Settings -> Output options -> Complete individual objects) for very long time. This approach has both pros (less travels and stringing, smaller cost of a print fail) and cons (possibly longer print time because of cooling-related slowdown). However, printing objects sequentially also means that the print head has to travel downward after an object is finished, which opens a possibility of a collision with another object printed previously.

Until now, it was up to the user to decide whether current positioning and ordering of objects will lead to such a collision or not. While PrusaSlicer had a very crude check for collisions and while it showed outline of the extruder clearance area in the scene, it was quite misleading and giving extreme amount of false positive detections, rendering it hardly usable.

These times are now gone:

In addition, 3D model of the extruder is rendered when browsing through the Preview using the horizontal slider (as seen above). This is to help the user asses the situation. When a collision is detected, an error message is shown informing the user about which object was crashed into. The error does not block export of the G-code.

As of now, the feature is only provided for Prusa printers (except MK2 and HT90, the latter of which will be added before 2.9.1 final), because it requires detailed information about the extruder geometry. Printers by other manufacturers may be added later, if we are provided with the necessary data by the community. The exact format of the data may still change at this point (in general they are reasonably simple sets of extruder slices in heights where they change significantly plus the model for visualization). Testing and collecting feedback on the function as a whole is a priority at this point.

When PrusaSlicer does not have this extra information, it falls back to a very simple generic model based on extruder_clearance_radius and extruder_clearance_height config options. These options are in slicer for years and were used for the crude sequential printing check, we decided to keep them for this single purpose. The values were moved from Print Settings to Printer Settings, as they describe the physical geometry of the printer. The "fallback" model used for the algorithm is seen on the picture below, printing MK4 parts on an Ender:

Note that the horizontal slider has two modes - it can either browse through the whole print, or just the top layer. For assessing sequential printability, the first mode is probably more useful. The switch was in Preferences, but we have now also duplicated in it the slider settings menu in the bottom right corner, so it is readily accessible:

The algorithm heavily relies on z3 solver. Thanks to Microsoft for developing the library and releasing its source code publicly.

Related to #1052, #1095, #1662, #6474, #7787, #8948, #10216, #10709, #11834, #12592, #12815 and possibly others.

Multi-material interlocking #11588

Printing with multiple materials is often challenging regarding proper connection between adjacent parts. Especially some materials do not bind well together, meaning that the boundaries form weak spots in the resulting print. The same problem (to a lesser degree) affects prints with multiple extruders of the same material. To alleviate these issues, PrusaSlicer now has an option of interlocking the neighboring parts together:

The option can be turned on in Print Settings -> Multiple Extruders -> Advanced, where one also finds a couple of related parameters.

The feature was originally developed in Ultimaker Cura and it was later ported into OrcaSlicer. The implementation in PrusaSlicer was ported from there, with only minor modifications. We would like to express our gratitude to everyone involved in the development of this feature.

Configuration options to simplify printing with different materials

While PrusaSlicer in fact supports many scenarios in multitool/multimaterial printing, it was never very user friendly to set everything up in the user interface. In 2.9.0-beta1, we introduces an additional config option to help setup printing with multiple nozzle diameters. In this release, we are adding a similar tool to help with bed temperatures. The bed temperature is defined in Filament Settings, and it is not intuitive to see what happens if two filaments with different bed temperature in the config are used.

There is a new option in Print Settings -> Multiple Extruders -> Extruders -> Bed temperature by extruder, which specifies the extruder to take bed temperature from. Setting it to zero (which is the default) uses the simple logic that the first layer temperature is always taken from the first printing extruder, and the same applies to the second layer (which has a separate temperature settings).

A slicing warning informing the user about using differing bed temperatures now contains a hint to use this new parameter.

Other improvements with respect to 2.9.0

• Added a new configuration parameter for speed for printing solid infill above bridges (Print Settings -> Speed -> Over bridges) so it is possible to slow this difficult-to-print infill without slowing down the entire print.
• Add a new configuration parameter for speed of solid infill on the first layer (Print Settings -> Speed -> First layer solid infill speed).
• When sending multiple beds at once into Connect, the upload file dialog no longer allows to select a filename. Only the "bulk" naming dialog is shown after a printer is selected. This means that individual filename defaults retain correct print statistics (estimated times etc), instead of being overwritten by the filename for the first bed. #14078
• There are three buttons in SLA Material Settings - Material printing profile which set the values of all the tilt-related fields to predefined values corresponding to the legacy Fast, Slow and High viscosity profiles.

Bugs fixed with respect to 2.9.0

• Fixed incorrect visualization of travels in Preview when custom z-offset was used.
• Fixed uncommanded move to a random location in rare cases (caused by an uninitialized variable), possibly leading into digging the nozzle into the bed. #13826, #14079
• Fixed incorrect size of exported thumbnails when slicing using CLI (since 2.9.0, the thumbnail from the 3MF propagates to the G-code).
• Fixed rendering of bed numbers in Preview so they never render on the toolpaths. Also, the bed numbers newly show when viewed from under the bed. #13814
• Make wipe tower position and rotation accessible in placeholder parser again. #13684
• Fixed update of "state icons" in the Preview thumbnails when using Object Manipulation panel.

Bugs fixed with respect to 2.8.1

• When object and support layers end up too close to each other in a print with a wipe tower, the wipe tower layer was extremely thin and therefore very large. This is now fixed by merging such layer.
• Fixed invalidation problem resulting in missing infill when "wipe into this object's infill" was used. #13779
• Fixed incorrect fan speed until the first toolchange in multimaterial prints when "Prime all printing extruders" was enabled. First primed tool speed was used instead of the first printing extruder. #13721
• Measure tool was incorrectly disabled when any object was sunk under the bed.
• Fixed processing of meshes with cavities in SLA slicing. #13786
• Fixed gaps in the wipe tower in the first layer, appearing in specific cases.
• Fixed two independent cases when slicer incorrectly reported a cryptic error message referencing negative spacing. One was in Arachne perimeter generator (#13429), the other in multimaterial segmentation (#13836).
• Fixed undefined behaviour leading to crashes when extra assertion level was enabled during compilation (and possibly in other cases). #13859
• Fixed extrusion collision detection between a single object and wipe tower. #13444
• Fixed incorrect "slicing status" icon in the Preview when manipulating with different beds.
• "Wipe while retracting" was not working correctly in cases the extrusion was a single line instead of a loop. A "wipe" in a random direction was...

PrusaSlicer 2.9.0

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Summary

​This is final release of PrusaSlicer 2.9.0, introducing multiple beds, scarf seams, Printables integration, improved support for multiple nozzle diameters, paint-on fuzzy skin and many more improvements and bugfixes. The final release fixes three bugs found in 2.9.0-rc1. See the release logs of 2.9.0-rc1, 2.9.0-beta1 and 2.9.0-alpha1 for the complete list of changes with respect to 2.8.1.

Important note for Linux users: As noted before, we are now using Flathub as the only official distribution channel of PrusaSlicer on Linux. The reasons behind this decision and what it means for you are described at the end of 2.9.0-alpha1 release log.

Bugs fixed with respect to 2.9.0-rc1

• Fixed a crash in a specific case when slicing multimaterial-painted objects (#13676, #13798).
• Fixed a crash when slicing multimaterial-painted objects on a printer with less extruders than painted.
• Fixed highlighting of the active bed in case that the bed has a big custom model which would overlap neighboring beds (mentioned in #13791).

PrusaSlicer 2.9.0-rc1

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Summary

This is the first release candidate of PrusaSlicer 2.9.0. This release fixes couple of bugs found in 2.9.0-beta1.

The release candidate saves its profiles into regular PrusaSlicer configuration directory. When you first run it, it will search for all configurations produced by alpha or beta versions and offer to create a copy of the latest one.

Important note for Linux users: As noted during 2.8.x releases, we are now using Flathub as the only official distribution channel of PrusaSlicer on Linux. The reasons behind this decision and what it means for you are described at the end of 2.9.0-alpha1 release log.

Bugs fixed with respect to 2.9.0-beta1

• Windows specific: Export G-code button in the right panel was flickering on mouse move.
• The Slice Now button did not update after loading an object from the shape gallery (#13777).
• Fixed undefined behavior when sending G-code to print host. The issue only manifested on macOS with address sanitizer (#13766, #13759, #13750).
• A tenth bed was offered to the user after loading the project already containing maximum number of beds (a visual glitch, it was not possible to actually use the bed).
• Fixed empty thumbnail after adding a custom object into the shape gallery (bug introduced in 2.9.0-alpha1).
• Fixed freeze after a communication with Prusa Account returned a specific error code. This bug was uncovered by a problem on the server side couple of days ago which affected many PrusaSlicer users (#13768, #13762, #13765, #13762, #13745, #13757, #13758, #13748). Extra countermeasures were applied on both sides and they should prevent this from happening again.
• Fixed incomplete update when switching from FDM mode to SLA: out-of-bed status of volumes and thumbnails in bed selector were not updated correctly.
• Fixed a crash during slicing introduced between 2.9.0-alpha1 and 2.9.0-beta1.
• Fixed a crash when switching application language while using the bulk slicing screen.
• macOS specific: Loading screen displayed when web content is being loaded did not show.

Localization

• Updated POT.
• Updated CS, PL, DE, IT, ES, FR, JA dictionaries.
• Updated RU dictionary (#13438, thanks to @AndylgTom and Dmitry Sorkin).

Note on localization on Linux

When installing PrusaSlicer using Flatpak, only English and the system language are installed by default. In case you want to switch PrusaSlicer to another language, it is necessary to configure Flatpak to use these languages first. For example

sudo flatpak config --set extra-languages "pl_PL;de_DE"

will configure Polish and German for Flatpak. It is necessary to reinstall the application after.
Running the command with additional --user parameter will only configure the languages for current user, in which case sudo is not required.

PrusaSlicer 2.9.0-beta1

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Summary

This is the first beta release of PrusaSlicer 2.9.0. This release introduces more improvement related to multiple beds, several other improvements and couple of bugfixes.

To let you enjoy the beta without worries, the beta builds save their profiles into PrusaSlicer-beta directory, so you may use the beta side by side with the current release without ruining your production configuration.

Important note for Linux users: As noted during 2.8.x releases, we are now using Flathub as the only official distribution channel of PrusaSlicer on Linux. The reasons behind this decision and what it means for you are described at the end of 2.9.0-alpha1 release log.

Multiple beds - bulk slicing and export

It is now possible to schedule slicing of all prepared beds without switching them manually. The bed selector dialog in Preview now has an extra button. Pushing it activates a "bulk slicing" mode, and PrusaSlicer will start slicing all the beds one by one. When it is finished, a combined print statistics is shown.

It is also possible to export all the sliced beds using the usual button in the right panel. It now opens an "Open folder" dialog, and after a folder is selected, an extra dialog appears where it is possible to change names of the individual files. One can also uncheck one or more of the beds to not export them. The same dialog opens when sending multiple G-codes to Connect.

Support for printing with different nozzle diameters

Experimental support for printing with different nozzle diameters on multi-tool printers, such as the Original Prusa XL, is now available for experienced users and developers. This workflow allows combining nozzles of different diameters (e.g., for fine perimeters and fast infill) but requires a few profile adjustments.

Key changes:

• Automatic extrusion width calculation can be easily enabled (Print Settings -> Advanced -> Automatic extrusion widths calculation), adjusting based on nozzle diameter.
• Automatic infill combining (Print Settings -> Infill -> Automatic infill combination) helps optimize printing when using larger nozzles for infill. This feature, inspired by OrcaSlicer, simplifies setup. Thanks to OrcaSlicer for the idea!
• It is now possible to use the wipe tower and supports with multiple nozzles of different size.

Important Notes:

• Some nozzle combinations may not be compatible. Be cautious as these setups could lead to failed prints.
• For detailed step-by-step instructions and limitations refer to our help.

Closes #13159, #13587.

Other improvements with respect to 2.9.0-alpha1

• When using slicer from command-line interface and slicing a 3MF, the thumbnail in the 3MF is used for G-codes. Because thumbnail generator relies on OpenGL, PrusaSlicer cannot easily generate its own thumbnail. #7878
• When multiple beds are used, each is now labeled with a number. The number also appears in the Bed selector dialog in Preview, along with a status icon informing about current situation of the bed (not sliced / slicing in progress / slicing finished).
• Autocenter feature was removed. The feature was a candidate for removal for many years, because it caused more confusion than good.
• Extruder stall detection is disabled for XL before ramming.

Bugs fixed with respect to 2.9.0-alpha1

• Loading binary G-codes into standalone G-code Viewer was extremely slow.
• Fixed issues with 'avoid crossing perimeters' feature (#13445, #13478, #12432, #13669).
• Fixed incorrect display of volumetric flow rate in preview when "Use relative distances" was switched off (#13623).
• Fixed never-ending loading cursor on Linux when loading webpage in WebView panels.
• Fixed arrange not arranging to front on XL (#13650).
• Fixed wipe tower not auto-disabling on single filament print on MM printer (#13649).
• Fixed export of M73 C lines to G-code to fix displaying remaining time to color change. This was partially fixed in 2.9.0-alpha1 already, but not in all cases. #4734, #12849
• Fixed couple of camera glitches.
• Fixed missing updates of shells in preview after moving object using the right panel.
• Fixed incorrect placement of objects after cut (they would end up on an unexpected bed). #13637
• Stopped displaying warning dialog with "Error running JavaScript" phrase (#12950).
• Fix objects incorrectly rearranging after saving and reloading a 3mf in 2.9.1-alpha1 (#13651).
• Custom G-codes and ColorChanges did not load from project when multiple beds were used (#13651).
• Object names emitted into G-code for Cancel Object G-codes are now trimmed. Very long names were causing issues when sending the G-code using OctoPrint (#13314).
• Changed reading of keyboard shortcuts in WebView on MacOS. Current implementation of wxWidgets's WebView has completely different approach to keyboard shortcuts. On Widows, all kind of WebView shortcuts are read and implemented while no "PrusaSlicer shortcuts" are read. On Linux it is opposite situation - only "PrusaSlicer shortcuts" are read inside WebView. It is not the best, but behavior on Windows and Linux is acceptable. While on Mac no shortcuts are read at all. So far we have added reading and handling of cmd + Q, cmd + M and cmd + R. In future we would like to unify shortcut reading on all platforms.
• Menu button "Reload from disk" and "Reload WebView Content" now correctly share "F5" shortcut. Reload from disk shortcut was not working in last release (#13693).
• Fix of clipping logic for clipping arcs with negative radius. (#13678).
• Fix splitting to object moving some of the just split object parts to a different bed (#13661).
• Fix of search bar losing focus while typing (#13691, thanks to @themanyone).
• Fixed slow generation of cancel object polygons by performing union operation of polygons incrementally.
• Prevent empty slicing notification when switching beds.
• Height range painting tool now always use world coordinates and thus works correctly with rotated objects (13631).
• During startup, non-flatpak desktop files of older PrusaSlicer versions are silently searched for and deleted. This is necessary for correct opening of our custom URL (used for login and model opening from Printables). Unfortunately searching for desktop files has troubles to search all possible paths due flatpak changing XDG_DATA_HOME and XDG_DATA_DIRS which stores potential paths for desktop file creation. Thus some old desktop files might remain in the system. In such case, it is possible to delete those inside the old version with Configuration -> Desktop Integration -> Undo.
• Fix of uninitialized ExtrusionLine when Fuzzy skin was applied on Arachne extrusions to fix combining Fuzzy Skin and Seam Painting (#13614).
• Fixed incorrect seam placement with painted fuzzy skin (#13640, #13614).
• Fixed negative seam gap values causing invalid extrusion generation (#13678).
• Fix missing update of preview when switching beds in 3D scene.
• Fix empty layers when multi-material painting and modifiers are used (#13645).
• Fix of ignored assigned extruders to modifiers when multi-material painting is used (#13645).

Infrastructure

• Fix CMake bugs leading to build errors on Gentoo and possibly other linux distributions (PR #13609 by @jmickelin building upon PR #13080 by @Rose-David).

PrusaSlicer 2.9.0-alpha1

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Summary

This is the first alpha release of PrusaSlicer 2.9.0. This release introduces support for multiple beds, Printables integration, scarf seams, better fuzzy skin and other improvements and bugfixes.

To let you enjoy the alpha without worries, the alpha builds save their profiles into PrusaSlicer-alpha directory, so you may use the alpha side by side with the current release without ruining your production configuration.

Important note for Linux users: As noted during 2.8.x releases, we are now using Flathub as the only official distribution channel of PrusaSlicer on Linux. The reasons behind this decision and what it means for you are described at the end of this release log. Thanks for your understanding

Multiple beds (#10704)

It is now possible to work with multiple beds in the scene. This allows the user to handle more complicated projects (which do not fit a single bed) more easily than before. This feature is already known to BambuStudio users (the implementation in PrusaSlicer is completely independent).

Beds handling

To make the workflow fluid and not intrusive to users using only a single bed, there are no buttons to add or remove beds. A new bed is offered anytime you are dragging an object outside of bed for more than 1 second (unless the object is dragged to the new bed position faster, in which case it shows up immediately). This allows to create a bed and place an object on it in a single operation. The beds are placed in a compact grid pattern, with a hard limit of 9 beds. One bed is always set as active, which is controlled by left-clicking it. Operations such as "Import STL" and similar are processed on the active bed. The individual beds can be thought of as almost independent projects, each having its own set of color changes, its own wipe tower and so on. Currently the only limitation is that all the beds must use the same configuration (i.e. you cannot have an MK4 bed next to a MINI).

Arrange

The Arrange button in the top toolbar was duplicated. The arrange function can either do the global arrange (as it always could) or arrange only objects on the active bed (which includes objects partially on it). The settings dialog shown when right-clicking the button is common to both.

Compatibility with older PrusaSlicer

To keep the number of changes to our 3MF project files as small as possible, the positions of the beds are not explicitly saved, but they are instead inferred from positions of the objects. The new project files can therefore be loaded into older versions of PrusaSlicer (they obviously do not show the extra beds, though). As for loading older PrusaSlicer projects. PrusaSlicer actually had minimal concept of virtual beds for many years, which is obvious from Arrange function. When there were too many objects to place on a single bed, PrusaSlicer would keep adding them spaced as if there were other beds next to each other. If you load such a project into PrusaSlicer 2.9.0, this situation is detected and the objects on these virtual "beds" are moved so they actually end up on a non-virtual bed in the grid.

Preview

When switching to Preview, a bed selector toolbar is shown in the top-right corner, which was the last remaining space where nothing was placed yet. We were considering a bigger reorganization of the Preview scene, but in the end we decided to purposefully leave the controls where they were so we do not break what people are used to. We are planning to do a general overhaul in future, so it makes sense to us to postpone the big changes to do them in one go. Switching the beds in Preview moves the camera so the bed switched to is in the same position as the one switched from. The 'Sliced Info' statistics and 'Export G-code' button in the right panel are related to currently active bed.

What is in the works

It is currently not possible to slice all the beds in one step. This will be added before the 2.9.0 final. We only released the alpha a bit early to start collecting feedback.

Printables integration (#13207)

Printables.com has been fully integrated into the PrusaSlicer ecosystem, complementing the earlier integration of Prusa Connect in version 2.8.0. Printables is now a persistent tab in the top bar, available to all users regardless of login status. While anonymous users can browse and download models, logged-in users gain access to additional features such as managing collections, viewing liked and downloaded models, and sending G-code directly to Prusa Connect.

On model pages, three key functions — Slice, Download and Print — interact seamlessly with PrusaSlicer. The Slice button, identifiable by the PrusaSlicer logo, mirrors the functionality of the browser version. Clicking it redirects the user to the Plater tab, where the download starts automatically. The destination directory for downloads can be set in Configuration -> Preferences -> Others. The download notification now includes a link back to the model page on Printables. Once the download is complete, the data is added to the Plater using the same logic as the drag-and-drop mechanism.

The Download button provides similar functionality with two key differences. First, the user remains on the Printables tab, with a simple notification confirming the download in the bottom-right corner. As with Slice, a detailed notification is available in the Plater tab, including a button to open the destination directory. Second, the downloaded file is not opened or added to the Plater.

The Print button is exclusively for logged-in users and enables direct printing of G-code files. A background check between Printables and Prusa Connect ensures printer model compatibility. If a suitable printer is detected, users can start printing directly from Printables without needing to slice or download the model. A printer selection dialog, similar to the upload dialog in PrusaSlicer, is displayed to complete the process.

Printables is implemented as a webpage within a WebView, allowing its content and functionality to improve independently of PrusaSlicer releases.

Scarf seams (#11621)

A feature dubbed "scarf seams" by the community is introduced. The main purpose of this feature is hiding visible seams on smooth perimeters. It is achieved by overlapping extrusions at the start and end of a perimeter loop. The name of the feature originates from a similar technique in woodworking called "scarf joint". It is possible to turn on scarf seams for both inner and outer perimeters and to turn it off for holes in a print (e.g. a hole for a screw). Also, by default, when scarf seams are turned on, it only generates the scarfs if the perimeter is considered smooth. This can be turned off. Currently, the scarf seams are best visualized using the "Actual volumetric flow rate" option in the preview legend. This way it is clearly visible where the scarf joint begins and ends.

In the image above there is a cylinder printed with both a normal seam and scarf seam. Number one is the scarf seam start, number two is the scarf seam end and number three is a normal seam. The scarf seam greatly reduces the visibility of the usual seam. Yet, it is not a silver bullet as it may generates a new "ghost" seam, albeit way less visible than the original seam.

Settings related to scarf seams are located under Print Settings -> Layers and Perimeters -> Advanced.

It is important to note that scarf seams are not our original idea. As far as we know the original idea came from @MichaelJLew in #11621 and simultaneously from @vgdh in SoftFever/OrcaSlicer#3211. The feature was then implemented by @Noisyfox to OrcaSlicer in SoftFever/OrcaSlicer#3839. Even though our implementation is original (because of our specific code base needs), for the most part the functionality mimics the available functionality in OrcaSlicer. We would like to express our gratitude to the many people that got directly or indirectly involved with the development of this feature, with a special thank you to @Noisyfox who did a lot of the heavy lifting required to implement it in OrcaSlicer.

Fuzzy skin improvements

• Since fuzzy skin was integrated into PrusaSlicer, it was always applied to the whole perimeter. This behavior had drawbacks, such as when fuzzy skin was applied to the modifier, objects were split into several regions, and each region had its own perimeters that divided the layer into several parts (#6881, #9787, #10264, #13508). This behavior was recently improved in OrcaSlicer by @Noisyfox, which was the base for our implementation.

• We incorporated several other fuzzy skin improvements (like poor randomness) into PrusaSlicer, which were developed by the OrcaSlicer community. Thanks to @Noisyfox, @SoftFever, @SeaRyanC, and @andrewboktor for improvements of the fuzzy skin.

• We believe that the above mentioned improvements will lea...