adding an inventory and container to an item (backpack)

[Vakror]

I have been trying for like two weeks to make a backpack item, searching everywhere and looking at SO MANY backpack mods, but I cannot find how to do it. Can anyone explain?

[ChampionAsh5357]

The concept is mainly just an item handler capability with an inventory screen. I would suggest attempting to make it first and then ask questions whenever you get stuck.