Ring of Ender
Handshake with the cosmic abyss. How romantic.
It can be created in a Crafting Table, via shaped recipe:
When worn in the Ring slot, it allows the player to open their Ender Chest inventory, by pressing related keybind (default: I).
The ring can be used from default game screen or from player's vanilla inventory (Creative or Survival). If any other screens or inventories are opened, the ring will not work.
It will also work in Spectator Mode, opening the Ender Chest inventory and allowing to view its contents, but not allowing to interact with them.