Not sure if I am following here... Wouldnt that just be printing out the invoice?
Would this work for you?
Item 1 data for invoice 1234
Item 2 data for invoice 1234
Item 3 data for invoice 1234
etc for invoice 1234
Item 1 data for invoice 1238
This is called a summary report and you can create it on a layout based on your line items table.
This post assumes the following relationship:
Invoice::InvoiceID = LineItems::InvoiceID