Merge Loops makes sewing garment seams in Blender fast and easy. No more

clicking and merging boundary vertices one by one. Just select, pick a tool,

and the seam is stitched.

1. In Blender go to **Edit > Preferences > Add-ons**

2. Click **Install...** and choose the addon `.zip` file

3. Enable it (check the box next to "Merge Loops")

4. Open the **N panel** in the 3D Viewport and find the **Merge** tab

> Tip: after replacing the file with a new version, turn the addon off and

> on again (or restart Blender) in the same preferences screen.

The addon works in **Edit Mode** on **vertex selection**.

- Select a mesh → Tab into Edit Mode (vertex select)

- Right-click a boundary/seam vertex most of the time

- For some tools you also select a **second point** (an end point)

The tools are grouped into four sections.

For fine control when you want to do things yourself.

| Button | What it does |

|---|---|

| **Highlight Border** | Toggles a blue outline around all border (boundary) edges |

| **Select Points** | Helps you pick the boundary points of a loop |

| **Loop Edges** | Selects the edges of the selected loop |

| **Equalize** | Balances the number of points on the two sides |

| **Select Match** | Selects matching boundary points across the seam |

| **Add Loops / Subtract Loops** | Adds or removes loop segments to match both sides |

| **Merge Edge Loops / Merge Center** | Merges the two selected loops together (center = 2 points case) |

One‑click smart merging.

| Button | What it does |

|---|---|

| **Slit Zip** | Opens/defines an open slit, then stitches it automatically |

| **Stitch loops** | Same button name appears while a preview is active — press it to apply |

| **Ring Zip** | Merges a ring/dart seam using angle‑based detection |

While a **Slit Zip** preview is active, you also get:

- **Radius** slider — how close boundary points may sit to be paired

- Angle presets (Tight → Wide)

- **Brush Mask** / **Clear Mask** — mask areas you do not want stitched

- **Cancel (Esc)** — leave without applying

For closed boundaries (loops that form a ring).

| Button | What it does |

|---|---|

| **Closed Loop Selection** | Picks the two farthest corner points of a closed loop |

| **Merge Closed Loops** | Merges the two arcs point by point (walk the whole loop) |

| **Auto Equalize Counts** | On: equalizes the two sides before merging (adds loops) |

| **Relax Topology** | Smooths the seam area before merging (optional) |

The "sewing machine" tools.

| Button | What it does |

|---|---|

| **Loop Zipper Mode** (checkbox) | Switches the main button between the two tools below |

| **Single Zip** | Selected boundary point + its two boundary neighbors are merged (one zip) |

| **Loop Zipper** | From the start point, keeps zipping pair by pair until the end point, or to the end of the boundary if no end point is chosen |

> Loop Zipper how‑to: click a start boundary point, then a second point

> (the end). With 4 boundary edges at the start, it automatically picks the

> two edges pointing toward the end point.

| Option | What it does |

|---|---|

| **Relax Topology** | Smooths the seam before merging (like a sculpt brush). You can also relax UVs, adjust Strength and Radius |

| **Weld UVs** | Merges the UV vertices of the merged points too, then optionally **Move Island** (AUTO / FIRST / SECOND / OFF) |

| **Auto-Mark Seams** | Marks newly stitched edges as Sharp and adds **Crease** (0–1) |

1. Tab into Edit Mode (vertex select)

2. Select the start boundary vertex near the opening

3. In **Zipper Merge**, turn on **Loop Zipper Mode**

4. Select a second vertex as the **end point** (optional)

5. Press **Loop Zipper**

The seam is stitched in one click. Undo (Ctrl+Z) anytime to go back.

| Problem | Fix |

|---|---|

| Button is greyed out | You must be in Edit Mode with a mesh object selected, and have the right number of vertices selected (see each button) |

| "Start vertex needs >= 2 boundary edges" | That vertex is not on the boundary — pick a point on the seam edge |

| "End point was never found" | The end point is not on the loop of the start — select an end point on the same seam |

| Nothing merges | Turn off Weld UVs temporarily, or check Auto Equalize Counts |

| UV layout breaks | Check **Weld UVs** so UVs stay welded with the geometry |

Blender 5.2