Tutorials/Iron golem farming
NOTE: As of the 1.8 snapshot 14w04b, Iron Golems WILL drop iron if killed by sources other than the player, which is an UNnerfing from the previous snapshot. However, villager breeding is still changed, and there is indication that the villager chaining mechanic discovered by Tango Tek will no longer work. This is not confirmed, but if it is, the Iron Trench and Iron Foundry will no longer work. This posted as of 28/1/14
NOTE2: NimsTV Design Now Only Work if Give 3 Bread To Villager at 1.8
An Iron Golem farm is an easy way to acquire many iron ingots (and less useful poppies) with minimal effort after the initial setup. It is an artificial village (or several of them, spaced far enough apart to remain separate) in which golems are spawned and then either killed immediately, or moved to a holding cell (outside the village boundary, so that new ones can spawn in their place) for later killing. If you opt for the first method, you will either need to go AFK while camping out at the collection point, have a hopper collecting your items, or else check back periodically to collect your items before they despawn. This necessity can be avoided by using the holding cell method, which allows the golems to collect while you are working nearby, and then you can harvest them all at once when you are ready so that you don't miss any drops.
 Design by trunkz
This design created by trunkz has an average spawn rate of one iron golem every 6 minutes. It was the first efficient iron golem farm for the release version of minecraft; most of the other farms (like JL2579's one) are based on this one. It is more resource friendly, however the spawn rate is slightly less than JL2579's farm due to the central canal/water placement.
 Design by JL2579
This design created by JL2579 is very efficient, with an iron golem appearing approximately every 6 minutes. This design makes use of four iron golem spawning locations, two stacked on top of each other, and leading to a central collection point (resulting in an overall spawn every 1 1/2 minutes). The video tutorial is by docm77.
 Design by Nims
This new design by NimsTV is arguably a significant improvement on the original design by JL2579. Although it does not produce any more, it is more compact, which means the water streams are much easier to configure and there is only one villager basket. If you intend to build several duplicate farms in an array, this one will be more convenient because it takes less time.
 Designs by Tango Tek
These designs made by Tango Tek are by far the most space and time efficient iron farms.
The Trench compacts 32 villages inside the main building such that each village will spawn iron golems, meaning that they spawn very quickly. Iron golems will spawn an average of one every 10.6 seconds, meaning the farm will produce 1100 iron items per hour, or about a double chest of iron every 3 hours. The villages are compacted in this way using a village overlapping bug discovered by Tango that he calls "Village Chaining". A description of how this works can be found at 4:54 in the tutorial. Because the villages are so close together, they can merge if the player leaves the Overworld for more than 5 minutes or if the world is closed without the farm being built in the spawn chunks. This does not matter, however, because the farm includes an incredible amount of redstone systems that automatically rebuild all of the villages in a 20 minutes long process. You can watch the farm rebuild at 1:31:49 in the tutorial below.
WARNING: This farm uses likely one of the largest, most complex and expensive redstone systems that is still intended to be build-able in survival. Be aware of the huge amount of resources it will require compared to the other iron farm designs and only build it if you are fairly confident in your redstone knowledge and your ability to persevere through troubleshooting the farm. You have been warned.
Also note that the Iron Foundry, shown below, produces more iron, uses less resources, and is far less complex to build and troubleshoot. The only downside is that the farm below must be built in the spawnchunks, while the Trench can be built anywhere, provided it is given 20 minutes to start up each time the area is unloaded. This means that the Trench could be built on a server and be run overnight by standing inside it AFK overnight, whereas the Foundry would be built and then break as soon as the player logs out or the server is shut down. If you are building in single player or have access to the spawn chunks on your server, just build the Foundry.
The Foundry is a more recent iron farm that Tango released after discovering a simpler way to deal with the villages merging. This one increases the iron production to about 1700/hour using 44 villages instead of 32. The villages are chained together manually, meaning that the player places the doors and then breaks them himself, rather than using pistons and redstone logic. Therefore, it is much less expensive, and because of the different layout, it can have more villages and more iron produced. The build is still very time consuming but much easier to do and troubleshooting simply involves repeating the entire door placing step. The redstone consists of only a small clock and a dispenser system, and is overall much less complex and difficult to build than the Iron Trench. The villages stay loaded because an item is dispensed into a Nether Portal, meaning it travels to another dimension. This will load all the entities, including villages, in a small area around the portal for a short time. Thus, if you enter the Nether or End for more than 5 minutes (which would break the Trench) it does not matter because the villagers who see the doors keep them loaded and prevent them from being destroyed. You also do not have to refill the system that dispenses items into the Nether because the farm sorts the poppies from the iron and dispenses those into the Nether.
This design is also fairly comparable in size and building resources to some of the single village designs, so if you want to build an iron farm, this is by far the best one to use. The only significant resources required are building blocks for the structure and about 21 stacks of logs for the doors.
 Tower design
This design is good especially for survival. It will get you about a stack every 2 hours. It's pretty efficient, but for faster farms, use one of the above.
 Step zero - resources
To build an iron golem farm, you should have a fair amount of resources, such as cobblestone and wood, as well as a way to get villagers into it.
You will need:
- at least 1100 cobblestone (about 18 stacks)
- 64 doors (6 wood per door=384 wood planks or about 6 stacks.) (In 1.8 snapshots three doors are received instead of one)
- 18 water buckets (or 20 separate trips to a water source)
- 1 lava bucket
- 4 signs
- 10 iron ingots and 2 chests (This is for the option to use hoppers to collect items when you are away from the farm)
 Step one - Building location
To build the Iron Golem farm you should:
- Choose a good location. Don't build it far from your home or main base, because you want the golems to spawn even when you are not at the farm. An ideal spot is on top of your existing home or close to it.
- Gather the resources listed above.
- Follow the instructions below to begin building the base.
 Step two - Building instructions
Start by building a 4x4 cobble base.
Build in 4 blocks from each corner, then 3 blocks diagonal in both directions to build a triangle.
Next build a 1 block wide platform around this so the platform is now 20x20.
Now the top part is finished, the golems will spawn once there are 3 villagers in each of the holding cups. The next step is to build the golem grinder.