Tutorials/Villager trading hall
This guide seeks to teach you how to create a villager trading hall.
Villager trading halls maximize the number of villagers that can be easily reached. They also provide a way to quickly discard unwanted villagers and replace the ones that are discarded. They can take the form of a literal “hall”, with villagers lined up and waiting for the player to trade with them.
There are three parts to a villager trading hall: the input, storage, and output.
The mechanism that puts the villager into the hall must be able to close off the cell once the villager enters, to prevent more villagers from entering that cell. The mechanism must then open the next cell to allow for a villager to enter.
Sometimes, the player will want to keep a villager because it has valuable or worthwhile trades. These villagers must be accessed, so they stay in separate "cells" until a better villager comes along, at which point the player may wish to discard them. They must be protected from zombies, lightning, and other things that could bring harm to them.
A villager may come along with undesirable trades, or no trades at all. Also, a better villager might come along that would replace one that already exists in the hall. At this point, the player may wish to discard the villager, and the trading hall must provide a way to do so.
This discarding mechanism must be able to remove the villager from the cell and then open it up to allow for more villagers to drop in.
Once a villager is discarded, it is up to the player to do what they want with them. The most common thing to do is move the discarded villagers into one area, where they are killed by whatever means suits the player. It is not recommended to kill them manually, because that will lower the player's popularity, and if the popularity gets too low, any iron golems of that village will become hostile towards that player. An alternative to killing the discarded villagers is to store them for an iron golem farm, put them into a village, or put them to work in farms and breeders.
Designs come in all shapes and sizes, but they all have the same basic parts, as described above.