This tutorial assumes you already have some familiarity with the mod, or have at least followed the introductory tutorial:

• Getting Started

This page also touches on some concepts of asset generation, but those are only required for handling rare edge cases:

• Understanding Asset-Generation

• Equippables
  • In short
  • Non-humanoid armors
  • Equipment Assets
  • Asset-Generation quirks
• Trim Patterns
  • In short
  • Hiding Trims
  • Trim Assets
  • Coloured Trim Atlas (MC 26.2 and prior)

Write your module like you would for changing the inventory texture, but set the hook of your module to "equippable", and its assetGen to one of the "equipment/xxxx" assetGen presets:

{
	"items": [
		"diamond_helmet",
		"diamond_chestplate",
		"diamond_leggings",
		"diamond_boots"
	],
	"hook": "equippable",
	"assetGen": "equipment/humanoid",

	"...": "..."
}

Only the textures of equipments can be changed in this way, not their 3D model.

For humanoid armors set assetGen to "equipment/humanoid", and place your textures at:
/assets/<namespace>/textures/entity/equipment/humanoid/<model-id>.png
/assets/<namespace>/textures/entity/equipment/humanoid_leggings/<model-id>.png
(The same module will work for all four body-parts of an armor set.)

For elytras, use "equipment/elytra and put your textures in the wings layer:
/assets/<namespace>/textures/entity/equipment/wings/<model-id>.png

This hook works for all items that make use of the equippable component: Pet armor, Llama Carpets, Saddles, etc. Look for the matching assetGen preset, and put your texures in the folder for the approriate layer(s).

• Equipment Layer Types: All items that can theoretically be supported by Variants-CIT.
• Equipment History: What version of Minecraft each layer type was introduced in.

In the previous tutorial, the hook of your module was implicitely set to item_model, which caused it to override the item_model component of the target item.
For equippable, everything works fundamentally the same, excepts the module overrides the assetId field inside the 'equippable' component. The module will collect Equipment Models instead of item models, and asset-generation will look for textures in textures/entity/equipment/.

Each equipment model can have multiple textures, corresponding to the <layer> in the texture path above. The same module works for all body parts of an armor set, because each model it generates can includes the textures for all layers of an entity.

The existence of a single layer's texture is enough to trigger the creation of a whole model, but asset generators can only create JSON files with a fixed structure. The generated models will always have all the layers defined in their template, even if some of the corresponding textures were not provided.

Conversely, if multiple modules provide different layers for the same model but are using different templates, the layers from the two models will NOT be combined; only one of the generators will prevail at random, in a classic case of asset-gen conflict. In this case, you will need either a custom generator that provides all the layers in a single template, or to change the modules so they use models with different IDs.

To change the look of trim patterns, use the trim_pattern hook, the trim_pattern/humanoid assetGen preset, and place your textures at:
/assets/<namespace>/textures/trims/entity/humanoid/<model-id>.png
/assets/<namespace>/textures/trims/entity/humanoid_legging/<model-id>.png

{
	"items": [
		"diamond_helmet",
		"diamond_chestplate",
		"diamond_leggings",
		"diamond_boots"
	],
	"hook": "trim_pattern",
	"assetGen": "trim_pattern/humanoid",
	"...": "..."
}

Similarly to equipables, each trim module can handle all the bodyparts of an armor set. Only humanoid armors are supported.

Modules can't remove trims per-se, but they can replace them with an empty texture. Variants-CIT already includes such a model under the ID variants-cit:null. Simply make your module return this model.

With predicates:

"parameters": {
	"predicates": [
		{
			"modelId": "variants-cit:null",
			"precondition": { "..." }
		}
	]
}

With any Variant-ID based module:

"modelList": {
	"some-variant-id": "variants-cit:null"
}

For this particular model no assetGen option is required, and you do not need to edit the sprite atlas. All the required assets are already baked in the mod.

This hook overrides the value of the asset_id in the trim pattern referenced by the trim component.

Textures are the only assets you need to care about. The "trim models" are but a technicality, used by the mod to represent the textures of different layers under a single file. Although trim patterns have a vanilla resource type representing them, those resources are server-side and VCIT cannot interact with them as easily.

There exist only a single assetGen preset for this hook, and you will not need any other.

Trim textures are unique in that they need to have coloured variations for every material. VCIT does not automate this, and Minecraft only partially automates the creation of coloured trim textures. For those to be created, you must manually add your textures to the armor_trim atlas.

If your trims appear as missing textures, it is likely because you are missing this file in your texture pack:

/assets/minecraft/atlases/armor_trims.json

{
	"sources": [
		{
			"type": "paletted_permutations",
			"palette_key": "trims/color_palettes/trim_palette",
			// The list of permutations may vary with your version of minecraft !!
			// E.g: `copper_darker` does not exist until MC 1.21.9, when copper armor was added.
			// In doubt, check the vanilla version of this file and copy the permutations from there.
			"permutations": {
				"amethyst":         "trims/color_palettes/amethyst",
				"copper":           "trims/color_palettes/copper",
				"copper_darker":    "trims/color_palettes/copper_darker",
				"diamond":          "trims/color_palettes/diamond",
				"diamond_darker":   "trims/color_palettes/diamond_darker",
				"emerald":          "trims/color_palettes/emerald",
				"gold":             "trims/color_palettes/gold",
				"gold_darker":      "trims/color_palettes/gold_darker",
				"iron":             "trims/color_palettes/iron",
				"iron_darker":      "trims/color_palettes/iron_darker",
				"lapis":            "trims/color_palettes/lapis",
				"netherite":        "trims/color_palettes/netherite",
				"netherite_darker": "trims/color_palettes/netherite_darker",
				"quartz":           "trims/color_palettes/quartz",
				"redstone":         "trims/color_palettes/redstone",
				"resin":            "trims/color_palettes/resin"
			},
			// List all your trim textures here
			"textures": [
				"minecraft:trims/entity/humanoid/my_trim",
				"minecraft:trims/entity/humanoid_leggings/my_trim"
			]
		}
	]
}