Day 1 iron farm

ianxofour's day one iron farm, and the reason most survival worlds have iron by the end of the first week. Three villagers are dropped into a pit under a village, kept permanently frightened by a zombie in a boat, and the golems they summon fall into a suffocation trap. It needs no iron, no lava and no nametag to build, costs about thirty placed items, and goes up inside a single Minecraft day. The lava upgrade afterwards nearly doubles the rate.

• The villagers have to actually attempt to sleep before it starts. Stay down there at dusk and watch all three try it, and do not skip the night straight after loading them in.
• Remove every other bed in the village, or golems spawn there instead of in your farm.
• Build on the lowest point in the village and check for caves underneath. A golem sitting in a cave within 8 blocks of the beds blocks every further spawn.
• The fourth sign is not optional. Without it the fence gate catches fire and the spilled lava is miserable to clean up.
• On 1.21 move the zombie back a block or two so it cannot reach the villagers.
• If it stops after having worked, break the three beds, let the villagers re-link and sleep again. This is also the fix after a version update.