Installation

Blender 4.2+: Edit → Preferences → Get Extensions → ⌄ → Install from Disk, choose bomtag-1.0.0.zip. The panel appears in the 3D Viewport sidebar (N) under the BOM Tag tab.

Workflow

1. Choose a scope. Selected objects, the hierarchy under the active object (recommended for CAD imports: select the root empty), or the whole scene.
2. Choose how to match. Geometry (default) compares shape, Mesh data only groups linked duplicates, Name groups by cleaned name.
3. Scan Assembly. The list fills with one row per distinct part. The header shows items and total parts.
4. Review. Click a row to see its size and object count. Edit the name, material or note. Use Select Parts to see them in the viewport. Use ▲▼ to order the list the way your documentation reads, Merge to combine rows, X to drop a row (objects are kept).
5. Rename & Tag. Apply Names renames every object after its item. Write Properties adds bom_item, bom_name, bom_qty to each object.
6. Export. CSV, JSON or Markdown file, clipboard, or a text block inside the .blend.

Settings

Export formats

CSV columns: Item, Part, Qty, Material, Size, Volume, Note, Objects.

JSON

{
  "source": "gearbox.blend",
  "total_items": 6,
  "total_parts": 23,
  "items": [
    {"item": 1, "name": "Housing", "qty": 1, "material": "Aluminium", "size": "120.00 × 80.00 × 45.00 mm", "volume": 0.000182, "note": "", "objects": ["01_Housing"]},
    {"item": 2, "name": "Screw M4x12", "qty": 8, "material": "Steel", "size": "12.00 × 7.00 × 7.00 mm", "volume": 0.000001, "note": "", "objects": ["02_Screw M4x12", "02_Screw M4x12.001"]}
  ]
}

Markdown table with the same columns, also available through Copy as Markdown.

Using the tags in a web viewer

With Custom Properties enabled in the glTF exporter, every node carries its BOM data in extras. In Three.js:

gltf.scene.traverse((node) => {
  const bom = node.userData;
  if (bom.bom_item) console.log(bom.bom_item, bom.bom_name, bom.bom_qty);
});

Combine with the .callouts.json from CalloutTag: callout number = bom_item.

Ready-made viewer: see it live here The source is on github: copy index.html, put your exported model.glb next to it, and serve the folder (npx serve or python3 -m http.server).

Limitations

• Meshes only; curves, text and empties are skipped.
• Collection instances are not expanded.
• Size is the axis-aligned bounding box of each part, sorted largest first.