Is your feature request related to a problem? Please describe.
From a player perspective, I hate having to use commands or be limited by permission tiers for things I feel could be better represented with in-game crafting and item use methods. As a server admin, I'd like to give my players interesting in-game ways to make, use, and expand Ender Containers.

Describe the solution you'd like
What I'd like is a craftable item for players to use in place of "/ec" to remotely access their Ender Container.

Recipes:

Result: A named item that effectively performs the "/ec" command when right-clicked and allows access only to the first slot.

This could then be expanded by players through additional craftings, unlocking another chest with each iteration.
Recipe:

Result: Ender Container +1, +2, +3... until all slots are unlocked at +26

Additional context
I know this can be done to a limited extent with custom item plugins, but I don't believe any would allow me to change a player's permissions and grant them access to more slots based on the custom item they have crafted. (I'm also having difficulty getting custom items to behave as desired, but that's another matter.)

This would be a more interactive and fun way to let players decide how much storage space they want in their Ender Container and how much effort they want to put into obtaining their goal. This could exist as an optional and relatively automatic way for servers that want to reward player effort without having to set up a complicated permission structure to reward 27 different tiers of a single item alongside whatever other permission levels they already have going on.

I really like the idea of being able to craft custom enderchests, depending on their level etc. Very good idea, thank you!