Print the heart template. The largest heart is for the lids; the two smaller hearts, for positioning the edges. Trace the largest heart onto mat board twice, and cut out with craft knife. With marker, color along cut edges of mat board.
Spray 1 side of mat board heart with spray adhesive, and attach to colored paper. Cut along edge with craft knife. Repeat on reverse side, and then with second heart.Position medium-size template on 1 paper-covered heart, leaving about 1/8 inch all around, and trace with a pencil to create the guideline for gluing the edge. Position the smallest template on the other paper-covered heart, leaving about 3/8 inch all around, and trace with pencil to create the guideline for gluing the edge.
Cut box edges according to lengths on template: Make four 1-inch-wide strips of watercolor paper and eight 7/8-inch-wide strips of colored paper. With marker, color the exposed edge and about 1/4 inch down the sides of the mat board.
Working with a few inches at a time, squeeze glue along guideline, and bend side strip to attach. Repeat with all side strips, and let dry. Using spray adhesive, attach colored paper to both sides of each strip, exposing some of the marker-colored edge. Fill with candy, and close.