Place the raspberries in a small strainer. Holding the strainer over a chilled cocktail shaker, use the back of a spoon to push the fruit through the strainer. Discard the seeds and pulp remaining in the strainer.
Add the lemon juice, Sweet'N Low®, gin, and ice to the cocktail shaker. Shake very vigorously for 30 seconds, until the drink is somewhat foamy. Strain into a chilled cocktail glass. Top off the glass with 1-2 ounces club soda to make it frothier.