Preheat oven to 200 degrees F (93 degrees C). Dust egg molds with cornstarch.
Place sugar in a large bowl, stir to get rid of lumps. Make a well in the center and pour in egg whites. Mix and knead with hands 5 minutes, until well blended.
Press firmly into mold with the heel of your hand. Scrape off excess sugar with the straight edge of a knife. Unmold at once and place on baking sheets.
