ObjectHealer

ObjectHealer repairs meshes for 3D printing. Give it an OBJ, STL, PLY, GLB or glTF file and it writes a copy with duplicate vertices merged, normals pointing outward and holes filled, so the slicer gets a closed solid. The repair runs in Blender with no window open, from a drag-and-drop window or from the command line.

It started as the repair step of Splinter, a mesh segmentation tool, and became its own tool because most scanned or generated meshes need repair whether or not they get segmented.

Requirements

• Blender 4.0 or later. Verified with Blender 5.1.0 on macOS 27 (Apple silicon). Older versions lack the import and export operators it uses. ObjectHealer looks for Blender in this order:
  1. the BLENDER environment variable;
  2. /Applications/Blender.app, then ~/Applications/Blender.app;
  3. blender on your PATH.
• Python 3.10 or later. Tested on 3.10, 3.12 and 3.14.

Install

uv tool install object-healer
# or
pipx install object-healer

Raw scans usually need floater removal as well. It comes with the scan extra, which adds PyMeshLab:

uv tool install 'object-healer[scan]'
# or
pipx install 'object-healer[scan]'

Use

Window

object-healer

Drop files on the window, or use Browse files..., then click Heal All. Each healed copy is written next to its original as <name>_healed.<ext>. Hover over a finished row for the output path or the full error. Tick Strip floating pieces first for raw scans; the option is greyed out until the scan extra is installed.

Command line

object-healer heal part.stl scan.ply model.glb     # each to <name>_healed.<ext>
object-healer heal model.obj -o model.stl          # name the output; its extension picks the format
object-healer heal --strip-floaters raw_scan.ply   # remove scan debris first

Other options: --blender PATH picks a specific Blender, and --timeout SECONDS sets the limit for each file (default 300). An existing output is overwritten; the input never is. The exit status is 0 when every file healed, 1 when any file failed, and 2 for a usage or setup error, such as no Blender or a missing extra.

What the repair does

Each file gets its own Blender process, started with factory settings so your add-ons and preferences don't change the result. The file is imported, every mesh in it is joined into one object, and one Edit-mode pass runs:

Floater removal (--strip-floaters) runs before Blender. Blender's hole filling closes the object but keeps every disconnected piece, and a raw scan often carries specks of turntable and background. PyMeshLab removes each piece whose bounding-box diagonal is under 5% of the biggest piece's diagonal. The threshold is taken from the biggest piece rather than the whole file on purpose: MeshLab's own percentage is of the whole file's bounding box, so a single speck far from the object raises the threshold until it deletes the object too.

Limits

• It closes holes and fixes normals. It does not repair self-intersections, edges shared by three or more faces, or walls too thin to print.
• Hole filling closes every open boundary, including openings you meant to keep, so an open shell such as a single-surface cup comes back closed.
• Each filled hole becomes one polygon. STL and GLB output is triangulated, but OBJ and PLY output keeps that polygon for the next tool to triangulate.
• Duplicate vertices within 0.0001 units are merged. For a model in millimetres that is 0.1 µm; for a model in metres it is 0.1 mm.
• Materials from an OBJ's .mtl are dropped on import. An .mtl can name any image on disk, and GLB output would embed it. OBJ output never carries materials.
• With --strip-floaters, the mesh passes through PLY on its way to Blender, so UVs and materials from the input are lost. Scans rarely carry either.
• --strip-floaters needs faces, so it refuses a point cloud.
• Blender files (.blend) are refused, because they can carry embedded Python. Blender runs with factory settings and with auto-run of embedded scripts off.
• A glTF or GLB may refer to other files only through base64 data: URIs or relative paths that stay inside its own folder, with symlinks followed. Absolute paths, .. escapes and file: or web URLs are refused. Blender then gets a private copy of the model and of those files only, so a crafted model can't pull anything else into the output.

License

GPL-3.0-or-later. Copyright 2026 Aaron Montgomery. The repair script runs inside Blender through Blender's Python API, and Blender's license asks that such scripts be shared under the GPL. The window uses PyQt6, which is GPL as well. See LICENSE.

Provided as-is; bug reports are welcome, fixes are not guaranteed.