Print a Single Card
Open the card you wish to export, press the three dots 
in the top right corner of the card and "Export Card".
From here you can edit the export, which does not affect the card, selecting what tab contents or images you want and then press the print icon to print, or select "Save as PDF" to save the soft copy of your export.
Print Multiple Cards from the Project Library
You can export one or multiple cards at once from the Project Library.
Press the bookcase icon on the left of your Lumi screen 
From here you can search for a title or card name, or select "Cards" then the category or fields to filter your search. Once you have the card, or cards, in your search, you can select them by pressing the tick
and then select export 
from the bulk actions menu. Here you can edit the export and then print or save as a PDF.