Creating personal inventories

I have a system in mind that requires nodes with nested information for users. I'll outline the scenario:

A User can have x number of storage boxes
Each storage box can contain y number of document folders
User's can only view their own boxes and it's contents
User's can search through their boxes by unique box ids or by box contents
Only the system admin (me) can create/edit/delete nodes
On box creation the box details are enetered followed by the box contents.

So box123
could belong to Mr. J. Smith
and contain Folders:
Fld1, Chemistry LSA1
Fld2, Chemistry LSA2
Fld3, Physics LSA1
Fld4, Physics LSA2
Fldn, xxxxx... etc.

And box321
could belong to Mrs. A. Jones
and contain their items..

Each user will have a log on but they can only search for and view their own assigned box(es).

I have looked at CCK text field multiple to be used as the box contents but that won't work as multiple appears to only mean 3. I have also looked at Inventory Field but this is too rigid and won't allow for multiple items (unless predefined).

Please could anyone suggest some modules that would work together in order to accomplish this.

Many thanks, Tom