World Download Available Here
(The download included in this project is the design world)

Update 3.8.13: Facelift time!

- Got rid of the wonky brewing stand table thingys
- Added more detail
- Added more storage
- Made the lightning nicer
- Updated images - video is a little outdated but the main stuff didn't change

What is this thing?
This is a highly efficient, yet very compact mob farm, built in the skies high above my base.

How does it work?
When a mob - a Creeper, Skeleton or Zombie - spawns, it immediately hits a tripwire which triggers a row of pistons that pushes the mob into a water channel. This channel leads to the main channel and sends the mob to an adjustable fall of 23/24 blocks. Any item that the mob drops goes through a hopper into a double chest.

To go with the trap itself I made a snowball-shaped control room which has some simple, yet useful functions:

- Adjustable fall height, which means the trap can either be used as an XP farm without AFKing (due to the limit on natural mob spawns) or as an automatic farm with AFKing
- Special drop farming option, all it does is open the bottom part of the killing chamber, which allows to safely kill mobs with a special item (mobs with a special item survive the fall)
- Lava blade to automatically kill any mobs left in the killing chamber
- Creeper killer, which shoots an instant damage splash potion (rarely a creeper may survive the fall, and I guess you don't want things to get messy when you want to farm those special items...)
- Can indirectly be used as a record farm as well

The build
To make a long story short... yes, it took a while. The Minecart system leading to it and the control room went relatively fast, but the spawning room unsurprisingly took a long time, or more specifically the first layer of it.

I wanted to make it out of snow right away simply because it's nice and white so it kinda blends it with the sky, but it was only until the final moment when I came up with the snowball thing, which actually works quite well and looks decent.

the farm has 512 spawning spaces: 128 per column, 64 per row, 16 per chamber. It produces about 4000 items per hour - that is 7.8 items per spawning space. As a comparison, the mob trap on my old survival world which uses a flusher system and has 432 spawning spaces 'only' produces about 2000 items per hour, or 4.6 items per spawning space.