Hopper

It is a core automation part for collection and sorting; use it where item transfer is the build's purpose, and distinguish the hopper network from its chests and redstone control.

When it fits: Add it to an item-handling build after choosing source/destination inventories and the sorting layout.

The tradeoff: One source recipe run makes 1 and lists 5 Iron Ingot, 1 Chest at Crafting table; 1 recipe variant(s) for this output are grouped together. Verify access where the pack is incomplete. The craft is one block, but a working system needs multiple hoppers, storage, filters and often redstone; calculate the project, not one output.