Simply right-click a mob while holding a Creature Farmer to capture it inside the block. Place the block down and it will automatically generate that mob's loot drops on a timer. The captured creature spins on top of the block so you always know what's inside.
Start with a basic Copper Creature Farmer and work your way up through Iron, Gold, Diamond, Emerald, and Netherite. Each tier reduces the time between loot drops, from 4 minutes at Copper all the way down to 1.5 minutes at Netherite. Upgrade by surrounding your current farmer with the next tier's material in a crafting table.
The Creature Farmer pushes items downward into hoppers and chests automatically, making it easy to integrate into your existing storage systems. Each farmer has 5 internal slots that fill up between pushes, so nothing gets lost.
Powerful mobs like the Wither and Elder Guardian can be captured too, but they take twice as long to produce loot. Boss mobs are configurable in the config file.
Enchant your Creature Farmer with Looting before capturing a mob to increase drop quantities, just like killing mobs with a Looting sword.
Some creatures that normally don't drop useful items have been given custom loot when farmed. Bees produce Honeycomb and Honey Bottles, Snow Golems drop Snowballs, and Iron Golems yield Iron Ingots and Poppies.
Adjust cooldown times for every tier, set the boss multiplier, blacklist mobs you don't want captured, and define which mobs count as bosses. All through a simple config file.