Now you should have a spare S piece laying around. We're going to use this as our hole template. Take your straight edge and draw a centerline down the middle of the piece. It doesn't have to be perfectly center as we'll only use it to measure our vertical LED spacing. Now you need to measure the length of the piece and divide it by 14 so that your LEDs are equidistant from one another. Mine came out to be around 8mm apart. Mark little dots at each interval on the line.

Next you want to measure the width of your piece at each of the dots and put another dot exactly in the center of your measurement. This will keep the LEDs centered and make the final piece look nice.

Once all of your dots are in the right place and look centered, take the smaller of your drill bits and drill holes at the dots. You should have a piece that looks a bit like the one I made.

Once your 4mm styrene layers are dry, take your hole template and clamp it on top of the 4mm piece. If you're really good with the drill, go ahead and use your small drill bit to drill through the 4mm using the holes in your template. Otherwise use a pen or an awl to mark the holes, remove the template and then drill the 4mm piece.

Once you have the small holes drilled, take your 5mm bit and drill through the same holes to make them the full width. You should wind up with a piece that looks like Figure 4. (I also made a little light template to tell me what lights to put where.)

With all of the negative LED leads pointing the same way, clip only the negative lead so that they stick out only 2mm or so from the LEDs. Then cut a length of wire about 2 feet long and strip 6" of jacketing from the end of it. Mark the opposite end somehow so that you know it's the negative wire. Tin the bare wire with solder. (i.e. slowly heat up the wire and put solder on it so that you have a thin coating of solder along the whole length of bar wire) Then tin all of the negative lead connections on the LEDs. Finally solder each of the negative leads to the wire as in Figure 5.

Do the same thing for the other 4mm piece.