Are custom inventories implemented in sponge? And if they are, how can I create one? Thanks for your time
Yes they are.
Ill give you the starting point.
Inventory.builder()
From there you should be able to work it out 
Are custom inventories implemented in sponge? And if they are, how can I create one? Thanks for your time
Yes they are.
Ill give you the starting point.
Inventory.builder()
From there you should be able to work it out