Great question — answering as the UphillTech team:
Use this plugin from Woothemes: http://docs.woothemes.com/document/woocommerce-print-invoice-packing-list/ And modify the invoices by customizing your template (see the section "Creating Custom Templates" in the aforementioned webpage).
Full answer by barakadam: https://stackoverflow.stackexchange.com/a/29408786 (CC BY-SA 3.0).
Need it done for your business? UphillTech.