To create a customized postcard, cut a thin piece of colored cardboard paper down to about 3.5 by 5 inches or no bigger than 4.5 by 6 inches. Decide what kind of embellishments you want to use to decorate the card, and choose a patterned paper for adding a message; use glue to secure them into place. Once the glue dries, write your message, and add the addresses before sending it out in the mail.
Make the postcard rectangular, and keep all the embellishments inside the edges of the card. Create unique edges around the card using edging scissors that cut zigzags or half circles around the edge. Alternately, use craft punches to add shapes to the card in the corners or around the written text. Add stickers, photos, ink stamps or scrapbooking materials.
Before you glue the embellishments to the card, arrange them so the design fits and looks correct. Remember that the more you add, the heavier the card and the more the postage fee. Once your design looks right, use a pencil to mark where each piece is to be glued. After you glue the items, erase any pencil marks that show. Do not add anything that is easily knocked off of the card, as the card is not sent in an envelope to protect the embellishments.