Sculk sensor raid farm

Raid farm built on one villager in a boat, thirty minutes of work and under a thousand blocks. You drink an ominous bottle at the top of a pillar, ride down, and the raiders drop through a nether portal into a chamber where you kill them behind a safety trapdoor. A calibrated sculk sensor drives the timing, which is the one expensive part of the build and means a trip to an ancient city and an amethyst geode. At bad omen 3 and above the raid gives back ominous bottles, so it partly pays for its own fuel. Java. Hard difficulty is not optional here, on anything lower you get no totems.

Hard difficulty or you get no totems at all, and a bad omen 3 bottle or higher or you get no ominous bottles back either.
Keep fire aspect off the sword. It breaks the armor stand, and then you cannot reach the raiders behind the safety trapdoor at all.
From 1.21.11 put slabs on top of the nether portal and raise the glass wall next to it by one block.
If nothing spawns after you drop, stay up top until the raid actually starts loading and then jump.
Check for a missing glass block around the villager. Raiders spawning in there gives you one wave and no totems, which is the most common report of the farm half working.
Lift the villager with a happy ghast rather than fighting his pathfinding. Builders say that step took them half an hour otherwise.