Crack the walnuts carefully. Take the meat out carefully.
Clean out the shells. Spray with acrylic spray. Let dry. Turn over spray the outer shell.
Cut leather into small strips.
Take picture to put inside the shell carefully glue the picture to inside shell.
Match up the shell halves. On one side glue two leather strips to one side of the shell when dry put shells together. Add glue to the other shell half.
Let dry and open it may be a bit stiff pry it apart on the unhinged side.