Methuselah shulker farm

ianxofour's self replicating shulker farm, built around a single shulker that duplicates itself in a portal chamber while golems trigger it. The whole design was about longevity rather than speed, meant to run several hundred hours and produce around 100,000 shells before wearing out. Since 1.20.5 that no longer holds: shulker bullets stopped travelling upward through scaffolding, and the scaffolding was exactly what protected the shulker from its own fire. It still works with the block removed, but builders now report it stopping after roughly a thousand shells.

• From 1.20.5 shulker bullets no longer travel up through scaffolding. Remove the scaffolding directly above the shulker, or swap it for a button or an open fence gate, or the farm produces nothing at all.
• That fix costs the farm its lifespan. The scaffolding is what stopped the shulker hurting itself, and builders since report about a thousand shells before it stops rather than a hundred thousand.
• Spawn chunks shrank from a ten chunk radius to two in 1.20.5, so either build right on spawn or run a chunk loader.
• If your spawn chunks are jungle, desert or mesa, put the golem section in a small patch of river biome so they do not melt.
• Do not switch on the activator rail on the nether side until the reloading station is finished, or a curious piglin sends your backup shulker into the live farm.
• From 1.21 a lead on a boat is much the easiest way to get the shulker out of the End.