The 1.17 Caves and Cliffs Update introduces a new inventory management item: The Bundle!
This clip from Minecraft Live demonstrates the concept better than words ever could: (jump to 1:55:50)
Unfortunately, 1.17 is not there yet, and even if it was, this beautiful feature can't be used in many modpacks because there are so many mods and packs stuck on 1.12.
This mod attempts to solve this by implementing bundles as a mod for 1.12!
Currently not all the desired functionality is implemented, and there are some known problems that will later be solved in future versions of this mod:
1. It is currently totally possible to bring chaos to the creative inventory
2. Bundles can take items from slots where they shouldn't be able to
3. Bundles can put items in slots where they shouldn't be able to
4. There is no crafting recipe for bundles
This mod was originally created for use in the popular modpack RotN.