Make one copy on heavy cardstock and another on regular printer paper. Cut the heart out of the cardstock.  This will be your aperture opening for Iris Folding.  Use the other copy (heart only) as your template.  Once you have finished your Iris Folding, adhere a piece of paper over the back side, to give your box a nice inside finish.  Cut the box out and score along the dotted lines. All of these lines are folds that need to be done to complete the box.  Use 2-sided adhesive tape or glue to adhere the bottom and sides together.  Put a 'keepsake' on the inside and decorate box with ribbon.  This is great for showers, secret sisters gifts,  wedding mementos - the ideas are endless.  Use other Iris Folding designs.  You can make this box whatever size you'd like.  Experiment a little!

 
Simplicity of Iris Folding
Iris Folding Paper Craft - Square Box