I use quite a lot of armour mods and have been looking into tweaking the crafting categories in order to better sort the armors in a fashion I would like.
In the past I know the advice for adding a new crafting category was to make use of one of the 9/10 generic crafting slots that were left unused in the core game (although most of these have been used up by hearthfire and Dawnguard).
Since installing Dragonborn, I have noticed that Bonemold, Nordic Carved, Chitin (and presumably Stalhrim as well although I have yet to actually complete the quest that allows me to forge stalhrim) all appear as new crafting categories at the forge. As far as I can tell Dragonborn does not make use of the generic crafting slots, so does anyone know how they are added?
What confuses me is that Hearthfire uses up the majority of them, Dawnguard uses another one, leaving only two (one of which is in use by Immersive Armors in my game), and yet Dragonborn seems to be able to add another 4, without utilizing any of the empty slots as far as I can tell.
In the past the it was a matter of renaming one of the generic crafting categories (requiring a modification of a GMST record) and then association the appropriate material keyword with that category in the default object manager (which creates a modified DOBJ record in the mod when viewed in TES5Edit). Looking through Dragonborn in TES5Edit, the only GMSTs added or modified are new ones related to dragonflight, and while the DOBJ is changed, I can't find any references to the 4 new crafting categories, so I'm having trouble figuring out how it was done.