There ain't much to modify about Joy's mask, but then I remembered about the skull pattern seen in this image, so that's what I tried to kind of replicate, including the more "blocky" letters. It's not perfect, but I think it makes Joy's mask slightly more intimidating to the civs, even if just by a bit.
Didn't have the time to figure out how to make it dark or glitchy without either messing the whole thing up, or waiting for Starbreeze to let us create custom materials, unless I missed something.
INSTALLATION: Place the downloaded .PAK file right here - \PAYDAY3\PAYDAY3\Content\Paks\ ~mods
⚠️Hoxton:"It's not working lass."⚠️
If the .PAK mod is not working, make sure you have added the -fileopenlog launch argument to PAYDAY 3. For example, on Steam you can add that argument by right-clicking on PAYDAY 3, then Properties and lastly, General -> You should see the "Launch Options" box there, that's where -fileopenlog launch argument goes.
If it's still not working, make sure you don't have any conflicting mods.
Extra tip: If your game renders some textures properly while other ones look like garbage, add -dx11 to your launch options, see how that works, and if your game is gasping for FPS, try this mod out.