Tips & What Not to Do When Working on Models (specifically if you wish to put them back into the game)

1. Don't edit any character armature

• Bones/Character armature has data applied to it that can't be seen or modified in Blender. Modifying it means that there's a high chance it won't export
• This means deleting bones, renaming bones, adding bones, etc.

2. Don't delete Character objects (alternative provided below)

• Deleting character objects from their original place or renaming them causes issues when exporting (ex. deleting 13-body-0)
  • if you want to remove an object from a character such as 2B's dress, go into edit mode and remove the vertices rather than the object itself (object will still be intact)
• The .wmb file looks for the objects themselves when loading the game, so if they're missing or renamed, it won't load (modifying the contents within an object works -- edit mode)
• If you want to add your own objects in the scene and on the character, you can merge your object with one of the existing objects (ex. merging pants with 13-body-0)
  • just make sure that the new object is being merged TO the NieR object (so that the name and object data remain intact)
• This also means that you are limited to the same amount of objects that the character has

3. Try not to move things around in Object Mode

• Moving the NieR Objects around in Object mode (ex. 13-body-0 or 6-hair-0) will cause the origin to be misplaced
  • If you do move the NieR Objects around, make sure to set the Object origin back to the viewport origin
• The best way to deal with this is to move objects in Edit Mode
• Newer versions of Blender2NieR have an option at export that is enabled on default that centres all origins for you.

4. Make sure that models are always triangulated

• The NieR:Automata engine (and almost every other engine), reads models with tris. If it doesn't have it then you'll get an export error
• If you make a new model and it doesn't have tris, you can use the Triangulate modifier to turn your geometry into tris
• The exporter automatically applies the Triangulate modifier upon export but it's safer to apply/adjust it yourself

5. Make sure that no object has more than one material

• NieRAutomata's engine has a rule that only allows one material per object, and the game won't load if there are multiple
• You may accidently have multiple materials on one object when merging two objects so be careful.

6. Maintain NieRAutomata materials

• The game will only read materials with the properties that the character/model originally had
• Having new materials with no custom NieR:Automata properties can't be exported.
• Some models also have special materials that have to have a specific name; renaming them will prevent the game from loading.
• Make sure to completely delete any new, unused materials that you created before exporting.
  • You can delete materials by going to the blenderfile section of the outliner
    • Unlinking them from an objects isn't deleting them.
  • There is a purge materials option at WMB export that can try do this for you, but it does not always work.

7. Any new objects need to be weight painted

• If an object doesn't have a vertex group, the game won't know how it should move
• You can weight paint a character with according vertex groups (make sure it's identical to what the original was, or it will move obscurely)

8. You cannot have an empty object slot

• You can remove the all the vertices from an object to free up unneeded space, but make sure there's at least SOMETHING there to take it's place
  • The game requires at least one triangle per object slot, so an alternative is to create tiny triangle, and hide it inside the body
  • Make sure to give it a weight paint as well (the same vertex group as the part it's inside will prevent it from moving out of the body ex.bone2)

(Thank you DevolasRevenge)