In Minecraft, a villager becomes a leatherworker when it claims a cauldron as its job site block.
How a villager becomes a leatherworker
An unemployed villager (or a villager whose old job block was broken and is now jobless) will turn into a leatherworker when it has access to an unclaimed cauldron in the village. The game links villager professions to specific workstation blocks, and the cauldron is the workstation assigned to the leatherworker profession.
If the cauldron is later broken or claimed by a different villager, the leatherworker can lose or change its profession, as long as it has not been locked in by trading. Once a player trades with the villager, its profession and job site link are typically fixed, and it will keep being a leatherworker even if the cauldron is moved, until certain in‑game conditions cause it to refresh.
