Create solid colored worms by cutting them in half with a knife. Most brands of gummy worms come in a two-toned design, with one half one color and the other a different shade. Divide the halves you have cut into piles based on color. You will need four different colors with four worm halves in each color. For example, you will have one pile of four reds, one of four greens, one of four oranges and one of four yellows. Depending on the brand that you choose, you will have different colors from which to select.
Assign a different base to each of the four piles of differently colored gummy worm halves. One pile will be adenine, one guanine, one thymine and the other cytosine. Place the adenine and thymine piles next to each other and the cytosine and guanine ones together. These will create the base pairs.
Pair the base worms together. Slide one half of the pair onto one end of a toothpick, and the other base over the other. For example, if green is adenine and red is thymine, then you will have a half red/half green-covered tooth pick. Repeat for each base pair until you have eight total.
Build a sugar phosphate structure by linking full-sized gummy worms (phosphates) together with toothpicks (sugars). Think of these as the sides of a ladder. Lay the linked worms flat on a desk or work surface so that they are parallel.
Add the base pairs to the sugar phosphate back bone. Spear the full-sized phosphate worms with the edges of the base toothpicks. The base pairs will look like rungs on a ladder, with a strand of the full-sized gummy worm links on either side.