Split one item into 2 different items

A customer cuts a piece of wood so that there are now 2 pieces.

What is the best way to represent this in NAV ?

Example:

Item A is 10" x 12"

Customer cuts this into 

Item B : 5" x 12" 

and

Item C : 7" x 12"

So Item A is removed from stock and Items B and C are added to stock.

Does this have to be done manually using consumption journals or is there a more elegant way?

Thanks.