This little thing doesn't look like much, but holy hot DAMN does this thing crank out the drops. And, in the case of this pack (SkyFactory 2.5), loot bags. The kill zone is 3x3 with iron spikes and a vacuum hopper just above them, and is walled with glass so I can see the mobs dying to check the efficiency, and what it's getting. The spawn room itself extends 9 blocks each way from the drop shaft, excluding the shaft walls, and as you can see uses Extra Utilities conveyor belts.
Here's the inside. I had to wall off 3x3 areas to properly place those fans and prevent "safe zones" behind them. The walled off spaces are lit. The fans are why there are no branches of conveyors on the outside edges. I lit it with torches for this shot to shut it down and make it easier to see inside it.
This little thing has me running back and forth to collect loot bags a LOT. I had to put up those barrels for some of the other drops. I honestly didn't think it would work this well because there are still those safe zones where mobs aren't being pushed by the fans or conveyors. Yes, it gets Endermen and produces a good number of pearls.
Do note that I've only built a couple of grinders, and have done just a bit of reading on here for tips. I combined my knowledge of a water-channel-based grinder design, an idea to branch said channels, a tip to use XU conveyors, and a tip to use fans into this. If you want to build this, you'd be best off automating output sorting unless you want to lose drops to the vacuum hopper clogging up. Another thing you can do is stack levels and add more and more, all sharing one drop shaft, but remember that each level will add a shit ton more drops. At least until it starts hitting the hostile mob spawn cap.
