How can I have multiple menus?
You need to generate a new file inside the folder /plugin/ChestCommands/menu, it's recommanded to copy and paste the default menus, then edit them.
Can I use data values?
Of course, just add this row to the item: "DATA-VALUE: number"
Can I set the size of the stack?
Yes, add this row: "AMOUNT: number"
I want multiple commands to open multiple menus?
Each menu has its own command and item, don't worry about this.