Skin characters faster. Spend less time fixing weights.

Now significantly faster on large meshes.

Smooth Weights is an interactive, painting-style brush for relaxing and blending skin weights directly in pose, and no repeatedly switching in and out of Weight Paint Mode. It is built for character artists who spend hours cleaning up deformation weights by hand and want that work to go faster and cleaner.

Version 3 is a major release. Same tool, same workflow, but rebuilt in its core for speed, and shipping with an improved Symmetry Map for fast, reliable weight mirroring.

Faster overall

The whole tool was profiled and optimised for production-scale meshes. Measured on a real 90,500-vertex character with 83 vertex groups, at default settings:

• Flood smooth, surface mode: 3.5 s > 0.7 s | ~5×
• Flood smooth, volume mode: 31.6 s > 3.5 s | ~9×
• Flood smooth, volume mode, oversampling 4: 174.9 s > 6.6 s | ~27×
• Brush stroke update: 40–60 ms > ~8 ms | ~6×

Measured on the same workstation and scene in Blender 5.2; values are representative averages and vary by hardware and mesh structure.

See it in action

Take a look at the workflow videos to see what you can expect.

Smooth Weights - Add-on for Blender

Smooth Weights - How to use the Symmetry Map

What makes it different?

Smooth Weights brings the following production-oriented workflows together in one interactive tool:

• Volume smoothing — blend weights by proximity, not just topology, across gaps and overlapping geometry.
• Smoothing across island borders — keep mesh seams together during deformation by matching border vertices on neighbouring islands.
  
• Vertex-group limiting — cap the number of influences per vertex on the fly, keeping only the strongest weights.
  
• No mode switching — works directly in Object or Weight Paint Mode; every setting adjusts live while the brush is running.
  
• In-view selection painting — paint selections directly in pose, without entering Edit Mode, to constrain or protect areas.
  
• Topological and partial Symmetry Map with multi-island support — reliable weight mirroring even on imperfectly symmetrical meshes.

Symmetry Map

Mirroring is essential for skinning, but it breaks the moment a mesh isn't perfectly symmetrical, or is made of multiple islands.

Smooth Weights solves this with a built-in Symmetry Map. It supports both position-based and topological symmetry, handles meshes with multiple islands, and can even map partially symmetrical meshes by matching point positions. The mesh is processed for symmetry once, and the result is reused for every mirror operation after that. A gain in both accuracy (a mapped vertex never fails again) and speed (symmetrical points aren't re-found each time).

Once a map exists, it powers symmetrical brush smoothing plus dedicated Mirror Weights, Symmetrise Mesh and Flip Mesh operators, with automatic left/right vertex-group name swapping across common naming conventions.

Compatible with SHAPES for Blender. A Symmetry Map created in Smooth Weights is automatically imported by the upcoming SHAPES on first use. This way you can rig and skin here, then move to SHAPES for shape key work without rebuilding your symmetry.

Who it's for

Character riggers and skinning artists who want cleaner, deformation-ready weights with far less manual painting and less tool switching.

Feature list

• Interactive, painting-style weight smoothing brush
  
• Surface and volume-based smoothing
  
• Smoothing across island borders
  
• Built-in selection painting without entering Edit Mode
  
• Vertex-group limiting and vertex-group type filtering
  
• Locked vertex group support
  
• Symmetry mapping for fast, reliable weight mirroring (topological + partial, multi-island)
  
• Mirror Weights, Symmetrise Mesh and Flip Mesh operators
  
• Flood smoothing for whole meshes or selections
  
• Fully customisable keymaps and pie menu
  
• Optimised for large production meshes
  

Requirements

• Blender 4.2 or later (installed as an Extension).
• A mesh with at least two vertex groups.
  

What's included

• The Smooth Weights extension (smoothWeights.zip).
• Full user guide covering the brush, all properties, keymaps, tools and the Symmetry Map, accessible from the Smooth Weights panel.
  

New in v3

• Large across-the-board performance gains (see table): Up to ~27× faster on volume flooding with oversampling.
• Improved Symmetry Map: Multi-island, topological and partial mapping, with more robust storage and a one-click upgrade for maps made in older versions.
  
• SHAPES compatibility: Maps carry forward into the upcoming SHAPES for Blender.