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Vertex Volumes is a simple add-on that provides a Geometry modifier that allows you to define volumes using faces and per-vertex radii and offsets. The add-on uses faces to define volume by interpolating radius values between the vertices that make up the face.  Offsets can be applied to each vertex while retaining the source geometry for easy fine-tuning when modeling on other surfaces with the shrinkwrap modifier. This add-on is useful for detailing work, such as adding muscles on a character.