Internal Parts vs Customer Part (Additional Parts Catagory)

I am wondering if anyone has had this issue before. I have internal
parts that I need for example a Tool Crib Attendant to monitor
inventory and create purchase reqs. The big thing though, I do not
want him to be able to have access/view any of our customer part
information. I need a separate category in essence; I am throwing this
out for any ideas or previous solutions?