Combine, lookup and insert data

Its a big one, so this is only if you are bored...I will get it myself eventually.
Or just some rough advice would be cool.

OK seems to me like we are doing the same thing over and over, but thats what the man wants, so thats what he gets!


I am doing the WORKINGS sheet in the attached workbook.

First I need to combine the week totals on the VOLUME sheet for each product.
(the weeks to be added are input in WORKINGS sheet D4 & D5)

Each product is made up of a "casting" and a "backing plate" and sometimes other components too.
I need to look up the products using the PRODUCT LIST sheet to make a list of total components required (some products use the same components).
Column A is the product, G is the casting, I is the backing plate, then also K to P which also have qunatities.

Then combine similar components, adding the totals (if not already done).

Then put them into the correct row of the WORKINGS sheet (column E).