Valuation of Packing Material

We are being EOU, procuring (duly free) material in Containers.

can we use same containers for finished goods as packing material for clearance in DTA.

1)while considering Input cost of material -cost of Container is always included

2)There is no - corelation bet'n input container & o/p containers.....that can used as per customer requirement.

3)do we need to separate out cost of container for payment of Excise duty??? how???