Into 1/3 cup cold water, slowly sprinkle 3 packets of plain gelatin, stiring in between additions to dissolve completely before sprinkling some more. Add too quickly and you could develop lumps, which usually can't be broken up later.

Eventually the mixture will be like a paste or dough. Cover it with plastic wrap (you can leave the spatula in) and let it rest on the counter for 10 minutes, giving the water and gelatin a chance to dissolve.

Remove the plastic and move the stovetop-safe cup to a tall-walled pan containing steadily simmering water. No need to stir it while the mixture is melting down.

Add the packet of Jell-o, a little at a time, stirring slowly so as not to add extra air to the mixture, which will make your candies cloudy.

Turn off the heat. Add 2 teaspoons of ascorbic acid and stir gently to dissolve. Ascorbic acid is pure vitamin C and will add tartness to the flavor of the candy (as well as change up that distinctive Jell-O flavor). Add it at the last moment before cooling-- heat has a way of distorting fragile flavors.

Refrigerate the mixture for ~5 minutes. Notice as the air escapes the mixture, you're left with super clear candy at the bottom of the cup and cloudy candy covered in a layer of foam on top. Use the candy syringe to slurp up the clear candy at the very bottom. Use this syringe to make clear-lens LEDs, then slurp up the cloudy layer for some diffused-lens LEDs. =]

Also place your mold in the freezer 5 minutes before casting. The cool rubber will help set the candies faster.

Fill the cavities of the mold with candy. Start with a small area, then insert the 3D printed legs while the candy is cooling. There is a "sweet spot" where the candy is solid enough to support the legs but still molten enough to stick.

Put the mold in the freezer for a few minutes or in the fridge until you're ready to unmold your candy.

Bend and flex the mold to help the candy come away from the mold, and pull the candies out onto a piece of parchment paper.

Allow the candies to air dry if you wish to bag them up together (prevents sticking), or just present them to your friends and eat them right away!