Cream together butter, powdered sugar and coconut. Stir walnuts and condensed milk into the mixture. Roll into 1 inch balls and arrange on waxed paper covered cookie sheets. Refrigerate for at least 2 hours.
Melt chocolate chips and shortening top of double boiler over medium-low heat. Working in small batches, dip balls in chocolate until covered. Place on waxed paper covered cookie sheets and refrigerate. When firm, store covered in refrigerator.
