youtu.be/VlzmgGsuemEA postcard flyer has changed a lot, for the last couple of years, as it was originally created as a rectangular piece of pre-printed thick paper or thin cardboard with the intention of later being written and mailed without the need of an envelope as usual for mailing all the other type of flyer. Other shapes rather than the 4” x 6” had been also seen since all time and also in another sort of paper or thin wood.