Normal Align Tool

It was decided early on in the development of Alien: Isolation to take the approach of having defined rounded edges to many of the hard surface models.
To achieve this using just 3ds Max's smoothing groups greatly increased the triangle count on meshes and achieving this with normal maps proved fiddly and expensive due to each mesh requiring a bespoke normal map.
The answer came from Nathan Dearsley, a senior artists on the team at the time, who demonstrated the use of customised normals could achieve the desired look at no extra texture memory cost and with a lot less triangles - a win win scenario!
There were a few 3rd party tools which were designed to bend normals so they faced in the direction of any given face selection.
They worked as intended but all of them didn't consider the fragility of custom normals on editable poly meshes and how easily they break with any subsequent edits after the normals have been modified.
The Custom Normals tool I wrote produced the same results as the 3rd party versions but it importantly had a button which would recover the custom normals at any given time, even after the geometry has been edited and the normals broken.
The below animated gif demonstrates how custom normals break after a subsequent mesh edit and how the tool is able to successfully recover from the damage.