Materials:

clear plastic tubing, about 1 centimeter in diameter & 6 ft long
2 electrical wires (34'' each)
2 thick bendable wires (large enough to hold tubing but thin enough to wrap electrical wires)
9 thin metal wires (about 2 centimeters each)
LEDS (I used green, yellow, blue, and red)
resistors (100 ohm)
20-inch wooden dowel
wooden plank (3 1/2'' x 8'' x 1/2'')
silver spray paint
On/Off switch
switch box (optional)
AC wall adapter (5V output)
heat shrink tubing (for electrical wires; optional)
electrical tape (optional)

Tools:

soldering iron with solder
wire strippers
wire cutters
drill and nails
scissors
marker
crazy glue

Instructions:

1. Start by cutting the plastic tubing into two 18-inch pieces for the backbone and nine 3 1/2-inch pieces for the bases.  Make uniform dotted marks along the backbone every two inches.  Use scissors to cut marks into small holes.  Insert bendable wires into the backbone tubing.

2.  Using wire cutters, cut electrical wires into sixteen 2 1/2-inch pieces and two 7-inch long pieces.

3. Starting from the top and following the diagram below, bend back the anodes of two LEDs and solder them together.  If the anodes do not reach, use a thin 2 centimeter wire to connect them.  I used wire strippers to strip off the cable of some extra electrical wire, twisted the metal wire, and used heat shrinking tubes to secure its shape.


4. Next, solder a resistor to the cathode of one LED.  Insert the LED-resistor combination into a 3 1/2 inch tube.  For the first base, solder the other end of the resistor to ONE 2 1/2-inch electrical wire.  Do the same for the cathode of the other LED to ONE other 2 1/2-inch wire.  Insert the wires into the holes of the backbone tubes.

5.  Repeat steps 3 & 4 working your way down but this time for each base, solder TWO 2 1/2-inch wires to the resistor and the cathode of the opposite LED, as shown above, until you have nine bases completed.  Make sure to have the resistors all on the same side.  The model should look like a ladder, with two 2 1/2-inch wires sticking out at the bottom.

6.  Now, to build the foundation of the model, drill a hole midway through the wooden plank large enough for the wooden dowel in the middle.  Drill two more holes large enough for the bendable wires halfway through the plank, one about 1 1/2 inches away from the dowel to the right, another about 1 1/4 inches away to the bottom left, as shown below.


7. Glue the wooden dowel to the plank.  Spray paint the plank and dowel to desired color (I used silver).  Allow paint to dry.

8. After the wooden dowel is secure, carefully slip the DNA model through the dowel, intertwining the bases.  Slightly bend the model to get the thick bendable wires into the holes of the plank.  Glue the bendable wires.  Once dry, twist the model to achieve a DNA-looking structure (see images above).

9.  To get the model to light up, solder and heat shrink the bottom electrical wires to the remaining two 7-inch electrical wires.  If you have a switch box, make sure to feed the wires through the box before proceeding to solder them to the switch.

10. Connect the wire with all the resistors to the On/Off switch by soldering it to the second pin.  Finally, split the AC wall adapter wiring in order to solder one wire to the switch and the other to the remaining 7 inch wire (the one without resistors).  Use electrical tape to cover any exposed connections.  Close the switch box if applicable.

11.    Plug in AC adapter to wall, turn the switch on, and watch your DNA model glow!!