NOTES
This pack uses item models to add custom masks to Minecraft.
It does not require Optifine, CIT, or any other mods.
It DOES REQUIRE a datapack or in-game commands to access the masks.
This pack was made for Minecraft Java Edition version 1.21.4

How to use this resource pack
If not paired with a datapack, then you can use the following command to add masks to the game through cheats.
This command will give a recovery compass that is wearable in the head slot that has the item model of a blank mask and makes the equip sound that turtle armor would make.
A recovery compass was used since the only purpose it serves in the game is to look at it and mobs will not interact with the item and it cannot be placed on accident like a carved pumpkin can.
This command does work with other items as well should you choose to use something else as the base item.

/give @p recovery_compass[item_model="gobgrin:masks/blank_mask",item_name='"Example of Mask Name here"',equippable={slot:"head",equip_sound:"item.armor.equip_turtle",damage_on_hurt:false}] 1

In the case that you use the Gobgrin's Mask Pack Datapack, all you need to do is use a carved pumpkin in a stonecutter. All masks will be available as options.
The base item used for those masks are recovery compasses, so the game will be changing your carved pumpkin into a wearable recovery compass that has the appearance of a mask.
Once you've crafted the mask, you will not be able to change it or turn it back into a carved pumpkin. Choose wisely or have a pumpkin farm for it.