Create and modify vertex groups for a mesh, with an in-editor 3D view to select vertices.
Simply add the entire folder into your projects Assets folder, and attach the VertexGroups component to a GameObject with a MeshFilter.
After assigning vertex groups, they can be retrieved as followed (KeyValuePair<string, int[]> key contains group name, value contains vertex indices):
int index = vertexGroups.GetGroupIndex(yourGroupName);
KeyValuePair<string, int[]> = vertexGroups.GetVertexGroup(index);