Firstly: Defining Vessels
Vessels: aniyah is the plural of ina', and the plural of that plural is awan. Ina' refers to a vessel or container.  Jurists’ usage of this term is purely linguistic.
Secondly: Vessels Made from the Skin of a Consumable  Consumable refers to an animal the flesh of which is permissible to consume. Sacrificed Animal
It is permissible to take vessels from the skin of what can be consumed of animals as long as it has been sacrificed. Consensus has been quoted on the matter by Ibn Hazm and Ibn Juzayy.
Thirdly: The Ruling of a Dead  Dead as in non-slaughtered. Maytah refers to a dead animal that has not been sacrificed, but rather died due to some other circumstances. Often translated to carrion, but not necessarily decaying. Animal’s Skin after Tanning
Scholars have differed over the ruling of the dead animal’s skin after it has been tanned over a few opinions, the strongest of which are two:
The first: all dead animal skins become pure except that of dogs and pigs.
The second: tanning does not purify dead animal skins except of those animals that can be consumed.
This is thoroughly discussed in the chapter of removing najasah.