Please note that I made a mistake in my Gummi Candy post. The gelatin should be changed to 3 TBSP.
I just made some with a "jello-bean" mold out of frozen 100% grapefruit juice concentrate. I needed a whole cup of sugar plus some stevia and they're still tart but oh so good.
NOTE: They taste more like packaged fruit snacks than actual gummi worms but maybe they just need more gelatin to have that texture.