I'm just blindly guessing but you can try look at this: https://github.com/PocketMine/PocketMine-MP/blob/master/src/pocketmine/inventory/CustomInventory.php https://github.com/PocketMine/PocketMine-MP/blob/master/src/pocketmine/inventory/CraftingManager.php https://github.com/PocketMine/Pocke...rc/pocketmine/inventory/CraftingInventory.php