Stand this tower of straws in your container, with the flexible end of the straws toward the bottom. It needs to stand upright securely, but you also need enough volume.
Combine the raspberry gelatin mix and the unflavored gelatin in a heatproof bowl, with a pouring lip, if possible. Most of the recipes I’ve seen aren’t clear on how much unflavored to use; I went with all four envelopes, figuring the firmer, the better. Bring the water to a boil, pour into the gelatin, mix well. Allow to cool until lukewarm. I let mine stand about 45 minutes or so.
Once lukewarm, add the cream and the food coloring. Start with just a drop and continue to add until you like the color. Mix well.
Pour the mixture into the straws. It will rush out the bottom —duct tape or not — so you must be sure there’s enough volume in your container to take the overflow. I actually had to stand the cup I was using in another shallow container to catch it. This got extremely messy. Once all the mixture is in there, put the whole thing in the fridge and chill at least eight hours.
I was expecting trouble getting the “worms” out of the straws and I got it, but not in the way I had envisioned. The trouble came in when I tried to pry my tower of straws out of the cup — itself full of solidified gelatin worm material — in which they’d chilled. I eventually had to break the cup — fortunately, a cheap plastic one — to remove them. Then they stuck to the duct tape and the whole process became even more messy.
Once your worm-filled straws are free, however, run them a few at a time under warm water — protecting the ends with a hand — dry and, holding the top end of the straw, pinch and slide your fingers down the length of the straw so the “worm” slides out. This will take a while, especially if you used all 100 straws, so be sure you’re not doing this 10 minutes before your Halloween party.