Best way to decrement inventory

We are a printing company, producing a large variety of skus. At the simplest level imagine a poster, which might use a certain sqm of paper, and a certain number of mls of ink.

We have the paper, and ink setup in netsuite as inventory items.

All of our actual production happens outside netsuite (we use 3rd party software to pull down images, send them to printers, print shipping labels etc).

On a daily/weekly basis, these orders are then pulled into netsuite via csv as invoices. (e.g. 200 x 12×16″ prints ). At the moment the 12×16″ prints (in this example) are setup as non-inventory items.

I’d like to work out the best way to adjust the component inventory when this happens. It looks like using assembly items/kits is the way to go – but then it looks like we’ll have to go through lots of manual steps to “build” and “fulfill” these.

Is there a better way? Is this something we can automate for example? I guess if we imported as Sales Orders rather than invoices could we then automate the steps through to creating/sending the invoice?