So, Fulcrum is an API currently in the words, being created by a friend of mine, and it allows you to create custom items, blocks, gui's that isn't limited to the slots, you can remove the slots and add custom ones like a furnace or design a new interface.
You can even manage resource packs and load them with it in a more efficient way, and his working on custom mobs and sounds too.
These custom things do re-texture blocks and items, but it doesn't remove the original. It allows hundreds to be added at once.
The GUI is abit clever and it doesn't touch the original menu, but instead manipulates the over layed GUI that you don't see and that GUI allows you to manipulate it to how you want.
I'd like to see a Skript addon that hooks into this and allows us to easier create all these kinds of stuff easily.
You can see it here: https://github.com/VolmitSoftware/Fulcrum
And some docs can be seen here: https://brains.volmit.com/fulcrum/
You can even manage resource packs and load them with it in a more efficient way, and his working on custom mobs and sounds too.
These custom things do re-texture blocks and items, but it doesn't remove the original. It allows hundreds to be added at once.
The GUI is abit clever and it doesn't touch the original menu, but instead manipulates the over layed GUI that you don't see and that GUI allows you to manipulate it to how you want.
I'd like to see a Skript addon that hooks into this and allows us to easier create all these kinds of stuff easily.
You can see it here: https://github.com/VolmitSoftware/Fulcrum
And some docs can be seen here: https://brains.volmit.com/fulcrum/