How to structure database for multilevel packing items

I want to make an inventory system where items have multilevel packings e.g A carton has medium boxes , medium boxes 开发者_如何学Pythonhas small boxes and small boxes has 2 items. Please tell how to handle it by using sql server 2005 so that it can easily handle sale and purchase and it display exact inventory status of how much carton , medium, small boxes and items are in stock.

I would recommend nested sets for hierarchical data in a relational database.