You can create postcards from a few simple materials. First, you need either card stock or thick watercolor paper, as well as a permanent pen or marker, ruler, scissors and a pencil. You'll also need materials to decorate your postcard, such as permanent markers, washable markers, watercolors and frisket.
Measure the paper
Standard postcards are generally 4 inches by 6 inches, though they can be as small as 3 1/2 inches by 5 inches, if you prefer. Measure and mark the paper lightly in pencil.
Cut the paper
Cut out your postcards. Use a ruler if you are having trouble cutting straight lines.
Decorate the card
Decorate one side of the card any way you want. You can color or paint a design. Frisket is a type of rubber that you can use for resistance. You can paint it on the card, and paint or color over it. When you pull it off, your design is left on the card.
Let it dry, and mark up the other side
Let the design dry so you don't smear it. Once it is dry, turn over the card. Draw a vertical line down the center with a permanent market or pen, using a ruler. Make three horizontal lines in the center on the right side for the address. Let the ink dry on your completed postcard.