diff --git a/.specstory/history/2026-01-12_04-42Z-screw-head-size-comparison.md b/.specstory/history/2026-01-12_04-42Z-screw-head-size-comparison.md
index 81b8449..f9f067e 100644
--- a/.specstory/history/2026-01-12_04-42Z-screw-head-size-comparison.md
+++ b/.specstory/history/2026-01-12_04-42Z-screw-head-size-comparison.md
@@ -143,3 +143,40 @@ What type of hole are you making (through-hole, counterbore, or tapped)?
 
 ---
 
+_**User (2026-01-12 04:50Z)**_
+
+how to export print-ready STL from Blender?
+
+---
+
+_**Agent (model default, mode Agent)**_
+
+
+
+---
+
+
+Exporting a print-ready STL from Blender:
+
+1. Select your object(s) in Object Mode.
+2. File → Export → STL (.stl).
+3. In the export dialog:
+   - Check "Selection Only" if you only want selected objects.
+   - Set "Scale" to 1.0 (or adjust if your model is in a different unit system).
+   - Check "Apply Modifiers" if you have modifiers (Subdivision Surface, etc.).
+   - Check "Forward: -Z Forward" and "Up: Y Up" (common for 3D printing).
+4. Click "Export STL".
+
+Important checks before exporting:
+- Ensure the model is manifold (no holes, non-manifold edges, or inverted normals).
+- Check scale: Blender units = mm by default. Verify your dimensions are correct.
+- Remove internal geometry if not needed (to save material/time).
+
+Quick check for issues:
+- Edit Mode → Select All (A) → Mesh → Clean Up → "Select Non-Manifold" to find problems.
+- Use the 3D Print Toolbox addon (Edit → Preferences → Add-ons → search "3D Print Toolbox") for analysis.
+
+If you want, I can help check your model or set up the export settings.
+
+---
+
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