Now, get your DPDT switch and wire every pin of it, solder and heatshrink all of them.
You can have a little less cable mess if you get the two 12V pins of the switch together. To do so, solder a small cable on one of the pins and with an exacto knife expose a little bit of the copper wire of the long cable connected to the other DPDT's 12V pin. Solder the short cable to the long cable and heatshrink them.
Take a look at the switch on the left.
Now solder the DPDT's cables to the LM317's output and to 12V.
Get the bicolour led and solder the resistor to its cathode, remember to heatshrink it.
Solder the other two legs to the DPDT.
Get a long cable, solder all the LED's cathodes together and then the other end of the cable to ground.
I've used a 3.5mm panel mount jack to plug my fans. On the jack's positive leg solder the DPDT. Then solder a small wire on the jack's ground leg. BE CAREFUL! If you are using panel mount jacks and you solder the DPDT to the jack's ground leg, you're going to have a short circuit. The threaded part of this connector is ground.
Get a large cable and solder all the negative legs of the jack together and the end of the large cable to ground. Heatshrink.
You can use either stereo or mono plugs for your fans. Solder the red cable of your fan to the legs on the center of the plug and the black cable of your fan to the outer leg on the plug. You can plug a fan while the controller is connected, but make sure that the controller is in off position; if not, you'll make a short circuit.
I got a dead CD-ROM and I've ripped everything and used its case to put this controller inside. I've drilled a blank faceplate and put the LEDs, pots, switches and at the back of its casing I've drilled holes and placed the panel mount jacks together with a molex connector.
There you have it!