Simple Compact three villager iron farm

A small iron farm for three villagers and one zombie. A 5x7 chamber holds the villagers and the zombie side by side, golems spawn on the roof, water pushes them off the edge into a lava blade above the hoppers. It fits next to a base and needs no perimeter, and it makes a few hundred iron an hour, so it suits early and mid game rather than bulk production. Java only.

Once the villagers get on the beds they lose sight of the zombie and stop panicking, so the farm stalls, mostly during the day. Move the beds back one block and put the barrels in the floor in front of them, the workstation pulls the villagers back into view of the zombie.
Let the villagers sleep one night in the beds before you scare them. A villager that never claimed a bed will not try to sleep and stops spawning golems.
Golems get stuck against the sides. Replace the blocks around the golem area with wall blocks and carry the walls down the drop shaft.
The trapdoors on the beam come near the end of the video, minutes after the villagers go in. Place them first or the villagers wake up on the wrong side and walk out.
Do not crouch when you place the water on the stairs, it will not waterlog.
Java only. Golem spawning works differently on Bedrock and the creator says in the comments there is no Bedrock version of this build.