To craft these masks, you’ll need a life essence. They can be found in mineshafts, nether fortresses and strongholds, but killing any mob can give you one.
The chances to get one by killing a mob is of 1 to 1000, but you can change that in the config file (the lower the nuber is, the higher your chances are).
You can also set/unset an “enchantement” effect with the config file. Here is what a life essence looks like (with and without the enchantement effect):
Ok, now you have your life essence, you can make your mask.
Now, bake it in a furnace:
And you have an… an unstrung mask. Just add two strings and your mask is ready, you can even wear it !
The Sheep mask:
The Cow mask:
The Skeletton mask:
The Guardian mask:
The Spider mask:
The Creeper mask:
The Elder Guardian mask:
The Enderman mask: