miauu's Modifiers' Gizmo Aligner is a script for 3ds Max that handles gizmo alignment for the Symmetry, Slice and Mirror modifiers. Its core method lets you align a modifier's gizmo by picking three points in the scene, setting the gizmo's orientation from those points.
Beyond the three-point method, the script adds dedicated options for two modifiers. For the Symmetry modifier, "Align to Working Pivot's Plane" aligns the symmetry plane to any of the XY, XZ or YZ planes of the working pivot. For the Slice modifier, "Align to active grid" aligns the slice plane to the currently active grid.
The script is a commercial release from miauu, listed as free in this catalog. It supports Autodesk 3ds Max and 3ds Max Design from 2013 through 2026, covering a wide span of releases. Version 1.2 was last updated on 2025-12-16, and a demo video is available.