PHP: /*** @var Player $player */ $player->getInventory()->setChestplate(Item::get(Item::DIAMOND_CHESTPLATE, 0, 1)); EDIT: As of 3.0.0-ALPHA12, PlayerInventory::setChestplate has been removed. ArmorInventory is a new object for Players that contains the same methods PlayerInventory did for armor. Simply put, use this instead: PHP: /*** @var Player $player */ $player->getArmorInventory()->setChestplate(ItemFactory::get(ItemIds::DIAMOND_CHESTPLATE, 0, 1));