
Rather than trying to print a form, create a report which returns the same data as the form. Report's include a sorting and grouping mechanism which you can use to present the data in a way appropriate to the printed page rather than to a screen.
You might like to take a look at InvoicePDF.zip in my Dropbox public databases folder at:
This little demo file includes an option to return the current invoice in a form as a report. It also includes options to output reports of multiple invoices as PDF files, either as separate reports or as a single report of multiple invoices.