RINSE clean plastic containers and lids with boiling water. Dry thoroughly.
CRUSH raspberries thoroughly, one layer at a time. Press half the pulp through sieve to remove some of the seeds, if desired. Measure exactly 2-1/2 cups prepared raspberries into large bowl. Stir in lemon juice, low calorie sweetener and pectin crystals. Let stand 30 min., stirring occasionally.
FILL all containers immediately to within 1/2 inch of tops. Wipe off top edges of containers; immediately cover with lids. Leave at room temperature until set. (May take up to 24 hours.) Store in refrigerator up to 1 week or freeze extra containers up to 1 year. Thaw in refrigerator.