Ordering Items based on User's Customer

1. User wants restrict ordering of only some items based on customer. For example, a customer may order plastic items and other orders only metal parts. Can someone guide on personalization?
   1. 1.    You may try to manipulate the item identifier type in the customer ship to by setting as 'Customer". This will allows to make orders in customer items for that specific customer ship to - where in this requires to setup customer cross reference. This case when you try entering the parts in the order the LOV will display only the customer cross reference parts
   2. 2.    (R12 only) You can set the Item Orderability rules to populate specific set of items in an OU as per the rules defined.