Decal Tool

On Alien: Isolation the environment models had decals overlayed onto their surfaces to add in extra details and iconography.
There were a few options available to the artists for applying decals onto their meshes and one of them was via the 3ds Max Decal Tool I wrote.
Within the 3d assets content library were also folders dedicated to holding decal material assets.
Each decal asset was a t-page texture which itself contained multiple decals where, for each decal, a bounding box was defined.
When the Decal Tool was launched it scanned the 3d assets library and built a tree view containing all the found decal assets (see the left-side panel in the image below).
When the artist then clicked on any of the decal assets, from within the tree view panel, the associated texture would be displayed within the texture display panel. Within here the artist was free to then click on any of the one of the decals to select them.
With a target mesh selected in the 3ds Max viewport, and a decal selected within the Decal Tool, the artist would then click the 'PREVIEW MODE' button.
A UV mapping gizmo then appears on the mesh, with the selected decal projected onto its surface. Within this mode the UV mapping gizmo can be freely moved across the surface, in real-time, to visually determine where the decal will finally be created.
Once the artist was happy with the placement of the decal within the Preview Mode, the 'Paste Decal' button is clicked to generate the decal on the mesh surface as an optimised piece of geometry.