Install

Blender 4.2 or newer (recommended): extension zip. Download print_pack_batch-1.0.0.zip. In Blender open Edit > Preferences > Get Extensions, click the arrow menu at the top right and choose Install from Disk…, pick the zip (or drag the zip into the Blender window). The add-on is enabled straight away.

Legacy add-on zip: print_pack_batch-1.0.0-legacy.zip installs via Edit > Preferences > Add-ons, arrow menu > Install from Disk…, then tick Print Pack Batch. Use one of the two, not both.

The panel is in the 3D Viewport sidebar: press N and open the Print Pack tab.

Uninstall

Extension: Edit > Preferences > Get Extensions, find Print Pack Batch, arrow menu > Uninstall. Legacy: Edit > Preferences > Add-ons, find it, arrow menu > Uninstall. Disabling or removing it unregisters everything (panels, operators, settings, handlers); a running batch is stopped first and its report written. Presets: the legacy add-on keeps them in config/print_pack_batch/presets until you delete them. For the extension they live in Blender's extension user folder, which Blender may delete on uninstall. Copy the .json files first if you want to keep them (the folder is shown in the add-on preferences). Exports and reports are your files and are never touched.

Quick start

1. Print Pack tab > Folder > pick the folder with your STL / OBJ / PLY / 3MF files. Tick Include subfolders if the pack has folders.
2. Output folder: pick an empty or new output folder (it is created if it does not exist).
3. Checks & Fixes: choose your printer (bed fit). The defaults are safe for most packs; see Limits for the two exceptions (a small opening meant to stay open, and the size guess for sub-millimeter parts).
4. Press Run Batch. The status bar shows the file or object being processed; Esc stops after the current one.
5. Press Open report. Every model has a status: OK nothing was needed, FIXED something was repaired or rescaled (listed), WARN look at it (the issue is listed), SKIPPED not exported (the reason is listed).

What gets written

• Per model, next to each other: name.stl (binary), name.3mf (with the preview as a thumbnail of at most 256 px; none when Previews are off), name.obj (if on), name.png (preview). With Mirror subfolders the input's subfolders are recreated.
• In the output folder:
  • Reports: print_pack_report.html, print_pack_report.csv (UTF-8, opens in Excel) and print_pack_contact_sheet.png (48 models per page, rounded up to full rows: _2.png, _3.png for more). Each report and sheet this run writes replaces the earlier one, and sheet pages left over from a bigger earlier run are removed; a report or sheet that is switched off is left from the earlier run (delete it if it would confuse).
  • Reserved names: a model called print_pack_report or print_pack_contact_sheet (or print_pack_contact_sheet_2, …) in the output folder is exported as …_model.
  • Journal: a hidden .print_pack_journal.csv records every model right after it is exported. It lists your file names and statuses: leave it out when you zip the folder for customers. To forget earlier runs, delete both the journal and print_pack_report.csv. Run one batch per output folder at a time: two Blenders writing into the same folder can lose each other's journal rows.
  • Re-runs: if Blender is closed or crashes during a long batch, run it again with If the file exists = Skip model and it continues where it stopped. The report keeps the earlier rows of the models that were not processed again (marked "from an earlier run") and their previews stay on the contact sheet. Esc in such a run works the same: once the current file or object is done, the earlier rows of the files not reached (also SKIPPED ones) are added in short steps, so the window stays responsive (the panel shows Stopping: writing the report). The live counts include the unchanged models. If the batch is stopped by File > Open or by disabling the add-on, those rows are added without reading their previews again: the HTML links the PNGs and their contact-sheet tiles stay empty until the next run. Stopping a batch before its first file leaves the earlier report alone.
• Files are written to a temporary ….ppb-part file first and renamed when complete, so a full disk never leaves half files.

Settings

Every setting has a tooltip in Blender. Defaults as shipped:

Printer presets:

• Bambu Lab X1 / P1 / A1 (256 × 256 × 256 mm)
• Bambu Lab A1 mini (180 × 180 × 180 mm)
• Bambu Lab H2D, single nozzle (325 × 320 × 325 mm)
• Prusa MK4 / MK4S (250 × 210 × 220 mm)
• Prusa MINI (180 × 180 × 180 mm)
• Prusa XL (360 × 360 × 360 mm)
• Creality Ender-3 V2 / V3 (220 × 220 × 250 mm)
• Creality K1 / K1C (220 × 220 × 250 mm)
• Voron 2.4 350 (350 × 350 × 340 mm)
• Elegoo Saturn 4 Ultra, resin (218 × 123 × 220 mm)
• Elegoo Mars 5 Ultra, resin (153 × 77 × 165 mm)
• Anycubic Photon Mono M5s, resin (218 × 123 × 200 mm)
• Custom (your own size)

Name pattern tokens:

• {name} the model name: the file name without extension; for split 3MF files file_object; for objects the object name.
• {index} the number of the source file in this batch (001, 002…). Adding a file earlier in the sort order renumbers the later ones, so do not combine {index} with Skip model re-runs.
• {date} today, e.g. 2026-11-05. Not with Skip model re-runs or a resume after a crash: on another day every name changes, so the whole pack is exported again.
• {size} e.g. 52x40x31mm (one decimal below 10 mm: 2.0x0.5x12mm). With Skip model re-runs, a changed unit or decimate setting changes the names, so those models are exported again.
• {folder} the subfolder (slashes become _). {source} the source file name without extension (Selected Objects: the full object name, ".001" included).

How the pipeline works (per file)

1. Read (STL, OBJ, PLY, 3MF). Coincident corners are joined, collapsed triangles are dropped.
2. Units: 3MF files are converted from their own unit. STL/OBJ/PLY: meter files (largest side below the meter limit) are multiplied by 1000; probable inch files by 25.4 if Rescale inch files is on, otherwise they get WARN; Force scale multiplies every STL/OBJ/PLY file (3MF files keep their own unit).
3. Fixes, in this order: merge by distance (vertices in the same grid cell of that size), duplicate faces, degenerate faces, crumbs, consistent normals, fill holes, inside-out shells. Degenerate faces with a tiny edge are collapsed; long thin slivers are kept because removing them would change the shape. Crumbs must be smaller than the size and than 2% of the model, and are kept when the file is probably not in mm. Holes are closed with a centroid fan (not the outline of a flat sheet). Inside-out shells are turned outwards; an inner shell of a hollow model stays a cavity.
4. Orientation: lay flat (optional), drop to bed, center.
5. Decimate (optional), then the final checks and bed fit.
6. Preview, export, report line.

Selected Objects

Source = Selected Objects processes each selected mesh, curve, surface, metaball or text object as drawn: modifiers applied, in world space (location, rotation and scale, also negative scale). Everything it instances is included: a collection instance (this is how linked assets usually arrive), Geometry Nodes, particle and vertex/face instances. Linked library objects and collections work (they are only read). Cameras, lights and empties without instances are listed as SKIPPED. The objects themselves are not changed. Objects are looked up again for every step, so deleting or undoing during a batch gives a clear "deleted" row instead of a crash.

Size of a Blender unit (1 Blender unit =, default Automatic): the untouched default scene (Metric, Unit Scale 1.0, Length in meters) counts 1 unit as 1 mm, exactly like Blender's own STL export and import. So a model imported from an STL comes out at its original size. A scene with a changed Unit Scale follows it (0.001 = 1 mm per unit, 0.01 = 10 mm). So does a scale-1.0 scene that shows lengths in mm, cm, µm or km (you model in real meters), and an Imperial scene. The panel shows the factor in use under the selection count, for example "1 Blender unit = 1 mm (like STL export)" or "1 Blender unit = 1 mm (Scene units)". Choose 1 mm / 1 cm / 1 m / 1 inch to override. A model smaller than the meter limit gets WARN ("very small: check 1 Blender unit =").

Workflows

• Release a Patreon / store pack: Include subfolders on, Mirror subfolders on, STL + 3MF, previews on. Upload the exports and use the PNGs and the contact sheet on your store page.
• Check a customer folder (print farm): export formats off = a check-only run that writes just the report and previews. Click the Warn button in the HTML report to show only those rows.
• Only new files: If the file exists = Skip model. Re-running on a growing folder exports only the new models (split 3MFs, {size} names and Selected Objects are processed again to learn their names, but existing files are kept); the report keeps the earlier rows. Skip model never replaces an existing file. A model whose export files all exist is skipped and its earlier row stays in the report. If some of its files are missing (a format turned on later, Blender stopped while writing), only the missing files are written. If a file with the model's name exists that Print Pack did not make (your own render, say), the model is skipped. An edited source file is not exported again: use Overwrite for that. Names belong to the source file that made them. When the files named rook were made by an earlier run for another source (rook.stl replaced by rook.3mf, a file moved to another subfolder with Mirror subfolders off, a source left out by Include), the new model is exported as rook_2. That is the next free name; its row says so and the old files are kept. Do not use {index}, {date} or {size} in the name pattern for this (see the tokens above).
• Heavy scans / sculpts: Decimate = Max STL size 25 MB keeps uploads under store limits.
• Print farm command line (no window; the add-on must be installed and enabled in Blender's preferences, or add --addons print_pack_batch for the legacy zip / --addons bl_ext.user_default.print_pack_batch for the extension before --python-expr, because Blender handles its arguments in order):
  blender -b --python-exit-code 1 --python-expr "import bpy; bpy.ops.print_pack.run(input_dir='/farm/in', output_dir='/farm/out', preset='farm')"
input_dir, output_dir, preset (a preset name or a path to a preset .json), source (FOLDER or SELECTED) and previews ('ON' or 'OFF') are optional. The summary is printed; the exit code is 1 when the batch could not start or stopped with an error (check the report and the output folder for what was written) and 0 when it ran to the end. Per-model results are in the CSV. The Help sub-panel has a Copy Command Line button. On Windows write paths with forward slashes (input_dir='C:/Packs/in') or as raw strings (input_dir=r'C:\Packs\in'): a plain backslash path is broken by Python's escapes. Previews use Blender's renderer, which needs a working OpenGL driver; a server without a GPU or display usually has none (--gpu-backend only chooses the API, it does not provide a GPU). Turn previews off there with previews='OFF' (or in a preset):
  blender -b --addons print_pack_batch --python-exit-code 1 --python-expr "import bpy; bpy.ops.print_pack.run(input_dir='/farm/in', output_dir='/farm/out', previews='OFF')"
  If the first preview fails anyway, previews are turned off for the rest of the batch with one note.

Presets

Presets sub-panel: Save stores every setting except the folders as a JSON file, Load applies one (an undo step in Blender's Edit > Undo History), the bin deletes one, Reset Settings puts the defaults back. The presets folder is shown in the add-on preferences (extension: Blender's extension user folder; legacy: the config folder). Settings are stored per scene (in the .blend). To start every new file with your own settings, set them and use Blender's File > Defaults > Save Startup File; for a file you already have, or a scene added with Scene > New, use Load. The add-on never writes settings into a file by itself.

Tips

• Drop a zip-extracted pack straight in: macOS ._name.stl files and __MACOSX folders are skipped (Skip hidden files).
• The report's filter buttons (All / OK / Fixed / Warn / Skipped) show only those rows and work offline; the file names link to the exports.
• A model that is FIXED lists exactly what was done (e.g. "filled 1 hole(s) of up to 12 edges"). Turn a fix off if you do not want it.
• Use {index}_{name} to keep the order of a pack in the slicer (not together with Skip model re-runs: a new file renumbers the later ones; the same goes for {date} and {size}). The report's # column is the same source number.

Troubleshooting

Messages in Blender (most mean the batch did not start and nothing was written):

Reasons in the report (the batch carries on):

Issues and notes in the report (the model is still exported):

Fixes in the report (status FIXED):

Processing notes (information only, the status is not changed):

Every problem also prints one line starting with Print Pack Batch: in the system console (Window > Toggle System Console on Windows). Send us that line if something looks wrong.

Limits

• No boolean union of overlapping shells, no self-intersection or wall-thickness repair (that is what our Print Fix add-on does per object). Shells are counted and reported.
• Holes are filled with a centroid fan (a point in the middle of the hole, triangles to its border); good for small holes, bigger openings are left for you.
• Volume is the sum of the shells (cavities subtract): parts that overlap (kitbashed models) are counted twice, so the volume is an upper bound there. Open models have an approximate volume.
• Merge by distance snaps to a grid of that size: two points closer than the distance but on both sides of a grid line stay apart (the hole check then reports the crack).
• Two defaults change a model on purpose. An opening with no more edges than Holes (edges) (12, for example a 12-sided pipe end) is closed: lower the limit or turn the fix off for such packs. A real part smaller than 1 mm (a resin gem, a pin) looks like a meter file and is scaled ×1000: set Unit fix to Detect, warn only or use Force scale.
• Inch detection is a size guess; cm files need Force scale.
• Geometry only: colors, materials, textures and 3MF print settings are not exported. A multi-plate slicer project becomes one model (or one per object with 3MF split).
• Selected Objects are exported as the viewport shows them: modifiers use their viewport settings (for example Subdivision Levels Viewport, not Render). The scene's instances (scatters, particles, collection instances) are read once, when the first object is processed: finish editing them before you start the batch.
• Memory: each model is processed in memory. Our 1M-triangle test peaks at 1.1-1.5 GB for the whole Blender process, so plan about 1.5 GB of free RAM per million triangles for binary STL, binary PLY and 3MF. Text files (ASCII STL, OBJ, ASCII PLY) need up to about twice that. If the system runs out, the operating system may close Blender. Files larger than 4 GB are skipped.
• During a batch the window responds between files; one very heavy file keeps it busy until it is done. Blender's autosave waits until the batch has finished.
• Previews run other add-ons' render handlers; a preview is skipped (with a note) while Blender renders something else.
• Tested on Linux only (automated tests and a GUI check); Windows and macOS are not tested yet.
• A big input folder is scanned in short steps before the first file: the panel counts the files found and Esc (or the Stop the scan button) works during the scan too.
• Hollow-model (cavity) detection has a work limit: when thousands of shells lie inside each other's bounding boxes (e.g. a chainmail sheet inside an inside-out base) it is skipped, and every inward-facing shell is treated as inside out. It usually takes well under a second per model, at most a few seconds for a model with thousands of nested shells.
• The CSV stores the export and preview paths relative to the output folder and the HTML header shows folder names only, so a shared report does not show your user name or folders. Nothing about a batch is stored in the .blend.

FAQ

See the FAQ tab on this page.

Changelog

1.0.0 (2026-11-05): first release.

License

GPL-3.0-or-later. © 2026 Sonneblom Digitaal. Contact-sheet glyphs are rendered from the DejaVu Sans font (Bitstream Vera license).