How to make the hearts:
Print out the heart template.
Transfer the template to the leather scraps of your choice and cut them out. Holes are marked on the template, then punch them out with the hole punch. Then thread the cord into a sewing needle and sew two heart cut-outs together using the sling stitch.This is how the slip stitch works:
With the slip stitch, you work from right to left. Insert the needle at the point where the holes have already been made, move to the right to the next hole, insert again and cut out again vertically at stitch height. Your cord is under the tip of the needle. Repeat the stitch to the right with the next hole.