I do not know if it will be possible, but it would be nice to add the new menu configuration system that have plugins like superiorskyblock, trmenu among others that goes by pattern or layouts, I have seen plugins that allow you to use together the slot system with the one I just mentioned, the difference is that instead of knowing the slot number you put a letter or name to the item and then place it in the layout forming a 6x9 example of a trmenu menu.
example menu
I do not know if it will be possible, but it would be nice to add the new menu configuration system that have plugins like superiorskyblock, trmenu among others that goes by pattern or layouts, I have seen plugins that allow you to use together the slot system with the one I just mentioned, the difference is that instead of knowing the slot number you put a letter or name to the item and then place it in the layout forming a 6x9 example of a trmenu menu. example menu