Fold your cardstock in half and trace half of the heart template as many times as you can. If you're using two colors, you want six of each, or a total of 12.
Cut the hearts out of the paper with the scissors. Fold the hearts in half if they aren't already.
Glue the twelve hearts in a stack, alternating between the two colors. Place weight on top (like a book) and let dry.
Cut a length of string. Unfold the heart stack and place glue on the first and last heart halves. Place the string in the middle and glue the pieces together. Let dry.
Hang your heart decor as desired using thumbtacks or Command strips.