This can be called to create a new item from code, for example CreateNewItem(‘AA01’);
static void CreateNewItem(ItemId _itemId, ItemGroupId _itemGroup = ”, ItemName _itemName = ”)    
{    
    InventTable         inventTable;    
    InventTableModule   inventTableModule;    
    InventItemLocation  inventItemLocation;    
    ;    
    ttsbegin;    
    // Master record in InventTable    
    select forupdate inventTable;    
    inventTable.initValue();    
    // If InventTable has other mandatory fields in addition to    
    // ItemGroupId and ItemId, they should be defined here    
    inventTable.ItemGroupId = _itemGroup;    
    inventTable.ItemId = _itemId;    
    inventTable.ItemName = _itemName;    
    inventTable.ItemType = ItemType::Item;    
    // You can put default DimGroupId, ModelGroupId, etc. here    
    inventTable.insert();    
    // InventItemLocation for default dimension    
    select forupdate inventItemLocation;    
    inventItemLocation.initValue();    
    inventItemLocation.ItemId = _itemId;    
    inventItemLocation.InventDimId = InventDim::inventDimIdBlank();    
    inventItemLocation.insert();    
    // Three records in InventTableModule (for Cost, Purchase and Sales)    
    // Of course, you can also set the price, unit and other values here    
    select forupdate inventTableModule;    
    // Cost    
    inventTableModule.initValue();    
    inventTableModule.ItemId = _itemId;    
    inventTableModule.ModuleType = ModuleInventPurchSales::Invent;    
    inventTableModule.insert();    
    // Purchase order    
    inventTableModule.initValue();    
    inventTableModule.ItemId = _itemId;    
    inventTableModule.ModuleType = ModuleInventPurchSales::Purch;    
    inventTableModule.insert();    
    // Sales order    
    inventTableModule.initValue();    
    inventTableModule.ItemId = _itemId;    
    inventTableModule.ModuleType = ModuleInventPurchSales::Sales;    
    inventTableModule.insert();    
    ttscommit;    
}
Import Items into Ax with Code – Microsoft Dynamics Community
