Gloppers!

Gloppers (glob hoppers) is a Minecraft mod that lets you filter your hoppers by renaming them with glob patterns.

The idea comes from LiveOverflow's Minecraft lets play, where these were silently implemented on his server to make his storage system easier to build.

A screenshot of a hopper's inventory, with the name "!*_ore,anvil"

Usage

First, install the mod. This mod is serverside only and will do nothing on the client (unless you're in singleplayer).

Once it's installed, rename a hopper in an anvil, prefixing with an exclamation mark. Add globs matching the IDs of the items you want to filter for, separated by commas.

Some example patterns:

!*_ore - Matches all ores
!iron_* - Matches all iron items
!totem_of_undying - Matches only the Totem of Undying
!*oak*,*cherry* - Matches all oak and cherry wood items

Note that you must use the internal identifier of the items, and not the item's display name (e.g. writable_book instead of Book and Quill). Don't add the namespace (the "minecraft" part).

Advantages over vanilla

Only materials required to use are iron and wood (no redstone)
1x1x1 footprint, compared to the popular 4x3x1 design
Ability to filter unstackable items
No junk items required

Usage in storage systems

Gloppers are most useful in storage systems. Instead of requiring redstone circuits that take up space, you can instead just design it like so:

A 2x4x1 schematic of a storage system, with a top row of hoppers, and a bottom row of one glopper and one chest

Items will only be sucked up from the top row to the bottom glopper if the pattern is matched.

Notes with mod compatibility

Lithium conflicts with Gloppers, and you need to turn its hopper optimizations off in lithium.properties (mixin.block.hopper=false).