How to Make It
Lightly coat an 8-inch square baking dish with cooking spray. Place ½ cup of the citrus juice in a bowl; sprinkle gelatin over top of juice. Let stand 5 minutes.
Combine water, 2 cups of the sugar, and remaining ½ cup juice in a medium saucepan; bring to a simmer over medium-high. Add gelatin mixture and cook, stirring constantly, until gelatin melts completely, about 1 minute. Pour mixture into prepared baking dish. Cover and chill until set, about 4 hours.
Just before serving, run a knife around edges of dish. Dip bottom of dish in hot water for 30 to 45 seconds. Sprinkle work surface with sugar, and invert dish onto surface. Cut gelatin into 1-inch squares, and roll in remaining ½ cup sugar, coating all sides. Serve immediately. To store, layer uncoated gumdrops between sheets of wax paper in an airtight container, and store in refrigerator up to 2 days. Coat in sugar just before serving.