[ QUOTE ] After several re-trys, I came up to a stage that I finally understand the mystery of the "offsetting" gizmo (boxy one~), I believe. To comprehead differnece between 2D, 2.5D, and 3D snap toggles, I had to played them with same setting for snap options: (1) Vertices and Midpoints were "ON" (2) Use Axis Constraints…