pcforms.com › diy-printing-blog › how-to-set-up-aHow To Set Up a Printer to Print on Custom Paper Sizes. Jun 15, 2018 · Our first step will be to make sure we have the right measurements. Measure twice, print once. (; 2. Open the Document to Be Printed and Open the Print Dialogue Box. Once your file is open you can enter the Print Dialogue by going to File > Print or by using the keyboard short cut “ctrl + P”. Here you can choose your printer.