👕Chestplate

To create a custom chestplate first open the file of your chestplate, if you don't have the file go first go to your first custom armor. Remember the name can be to anything you want, example: some_amazing_chestplate.json. If you came from your first custom armor you should have the base code with that you need to fill the spaces:

{
    "format_version": "1.8.0",
    "minecraft:attachable": {
        "description": {
            "identifier": "geyser_custom:the_identifier_of_my_armor_part",
            "materials": {
                "default": "armor",
                "enchanted": "armor_enchanted"
            },
            "textures": {
                "default": "textures/models/armor/some_amazing_texture_directory",
                "enchanted": "textures/misc/enchanted_item_glint"
            },
            "geometry": {
                "default": "(the next part change depending of which part of the armor is)"
            },
            "scripts": {
                "parent_setup": "(the next part change depending of which part of the armor is);"
            },
            "render_controllers": [
                "controller.render.armor"
            ]
        }
    }
}

In "identifier": "geyser_custom:" you need to add the identifier for your part of armor, remember this should be unique and you will need to remember it to create your custom mapping file, so now with the identifier it should look like this

IMPORTANT: The identifier should be the same name as the Minecrat Java resourecepack, you can make the identifier the name of the texture in Minecraft Java and in Minecraft Bedrock to avoid problems

{
    "format_version": "1.8.0",
    "minecraft:attachable": {
        "description": {
            "identifier": "geyser_custom:ice_chestplate",

Then you need to specify the path of the model texture for the armor in "textures": { "default": "" }, the texture for the chestplate always is going to be the layer_1. When you specify the path it should look something like this

{
    "format_version": "1.8.0",
    "minecraft:attachable": {
        "description": {
            "identifier": "geyser_custom:ice_chestplate",
            "materials": {
                "default": "armor",
                "enchanted": "armor_enchanted"
            },
            "textures": {
                "default": "textures/models/armor/ice_layer_1",

Now we need to fill "geometry": {} and "scripts": {} with the next:

            "geometry": {
                "default": "geometry.player.armor.chestplate"
            },
            "scripts": {
                "parent_setup": "variable.chest_layer_visible = 0.0;"
            },

With this your completed file should look like this

{
    "format_version": "1.8.0",
    "minecraft:attachable": {
        "description": {
            "identifier": "geyser_custom:ice_chestplate",
            "materials": {
                "default": "armor",
                "enchanted": "armor_enchanted"
            },
            "textures": {
                "default": "textures/models/armor/ice_layer_1",
                "enchanted": "textures/misc/enchanted_item_glint"
            },
            "geometry": {
                "default": "geometry.player.armor.chestplate"
            },
            "scripts": {
                "parent_setup": "variable.chest_layer_visible = 0.0;"
            },
            "render_controllers": [
                "controller.render.armor"
            ]
        }
    }
}    

With this you can continue creating the custom mappings for your item

📜Create the mapping file