DISCLAIMER: This is not guaranteed to be the fastest, easiest, or most foolproof method. This is simply the method that I've found works, and it's sure as heck better than the old method. Your results may vary.
Special thanks to George/Kingbore, Pear, and Rainer.
Prerequisites:
- DS Map Studio, and basic usage knowledge
- Yabber (w/ unpacked Elden Ring folder)
- FLVER Editor (latest version)
- .dds-Compatible Image Software (paint.NET, Photoshop, GIMP, etc.)
1. Find the AEG you're interested in. Track it down in ELDEN RING/Game/asset/aeg, make a new set of folders to match in your Mod Engine mod folder, and copy it over. Unpack it with Yabber, and open it with FLVER Editor. (As a side-note, it can open packed FLVER files too!)
2. Once it's open, click the Materials tab; this will show you a list of each material being used by the asset. You can find what textures go where using the Viewer Highlight button. Once you have the right material, hit Edit Textures.
3. In the new tab on the right, it will list each of the textures being used by this material. These will typically consist of at least one albedo map (the base colors) and one normal map (used for details like texture, bumps, dents, etc.). If the list appears empty, click on the "Apply MATBIN Textures" button. If prompted, navigate to ELDEN RING/Game/material, and select the allmaterial.matbinbnd.dcx file. This will then show the filepaths for each of the textures being used. Do some searching in asset/aet, and unpack them until you have the specific texture(s) you want.
4. Edit the texture(s) to taste. Ideally, use Paint.NET or Photoshop with Intel Texture Works, but other .dds-compatible software like GIMP may work as well. Once you're done editing, resave the .dds file. For albedo maps, be sure to resave them as sRGB. Normal maps (and also a few other things) use Linear. BC1-7 shouldn't make too much difference; BC7 is the least compressed, so use it for the best quality.
For a more in-depth look at texture editing, Honor Knight's Recolor Guide & Tutorial contains a lot of useful information. Give it a look as well, if you feel lost here.
5. Rename the texture files to represent a valid, unused AET, then edit the folder to match. Reflect these changes in the Yabber manifest. Once that's done: back in the FLVER Editor's materials menu, hit the "Browse" button next to the texture you're replacing. When prompted, navigate to the newly-renamed DDS file. Once you're done with everything, save the FLVER and close out of the editor. Rename the AEG files and folders to a valid, unused AEG, and edit its Yabber manifest as well. Repack both the AEG and the AET files.
6. Provided nothing went wrong: congrats! You may now revel in your creation.