Mix together 1 cup of the juice with the gelatin and allow the gelatin to rest for several minutes. This will allow the gelatin to "bloom," meaning that it will absorb the liquid and expand. This will make it much easier to dissolve the gelatin later.
Add the wet gelatin mixture to the saucepan with the remaining juice. Stir the mixture gently on low heat until the gelatin completely dissolves.
Prepare whatever gummy worm or leech "molds" that you want to use. Either use silicone candy molds, or try one of the other methods below.
Straw "molds"
To make gummy worms with straws, fill a tall, narrow glass with tightly packed straws. Fill the straws with the gelatin mixture.
Grill "mold"
Place a sheet of aluminum foil or parchment paper over the grill of your oven. Press the foil or paper into the spaces between the bars of the grill. It's easiest if you begin on one side and carefully work your way to the other side.
Fill molds
Pour the gelatin mixture into your candy molds. Using a syringe or dropper makes the job easier and less messy, but you can also carefully pour or spoon the mixture into the molds.
Place the molds over ice or place them in the fridge until the gelatin has set. If using the grill method, and the grill doesn't fit in your fridge, you can allow the gelatin to mostly set at room temperature and then move the worms to the fridge to fully set them.
Carefully remove the candies from the molds.
You can now serve and eat them immediately or store them in the fridge for later.
Video
Notes
Nutritional information for 1 gummy worm based on making 40 gummy worms with the amounts listed above and using lime juice as the base liquid sweetened with honey. It will vary depending upon the size of your molds and the juice used. For sour gummy worms, mix together some citric acid and sugar. Coat the worms immediately before serving them. (Coated worms don't store well as the citric acid will draw moisture from the gummy worms making them "sweat.") To help prevent the worms from sweating, use less citric acid (try using a fourth of a teaspoon of citric acid with 4 tablespoon of sugar) and coat the worms after they have dried out for a day or two.