Campfire slime chunk farm

A slime chunk farm you hollow out yourself, with flat slab platforms stacked through the chunk and two iron golems hanging in the middle to pull the slimes across. They fall onto campfires at the bottom and the slimeballs go into hoppers. There is no redstone in it and the whole cost is about 13 stacks of slabs, so the work is all in the digging. Build it under a deep ocean and you skip the cave lighting, which is the part that decides whether it works. The creator has since said in the comments that this design is outdated and points at a newer one on his channel, but builders keep confirming it, most recently on 26.2.

Clear a 22x22 area, not the 16x16 the video tells you at the start. It only corrects itself at the end and that is the top comment on the video.
Keep the beacon in the middle of the chunk until the platforms are finished, it saves you placing it twice.
For 1.18 and up the AFK platform goes at your collection level plus 114.
Build it under a deep ocean and there are no caves to light, which is most of the work gone.
Soul campfires kill faster than plain campfires.
You only need to mine one extra block on each side rather than three, and the platforms can carry up to y 40, which is as high as slimes spawn.