Step 3: Assemble the Cube!
You need to make a jig for this. I used foam core and basically drill some holes in a 3x3 matrix shape about 1/2 an inch between each hole.
now, when you have all of your LEDs in the holes and the pins are sticking up to the sky you need to bend the cathodes.
Easy enough to understand. The longer one is the positive and bear with me, this one is called the anode.
now you want to bend the cathode (the shorter one) the way the arrows go on this picture. Then when that cathode is bent it should be touching the other LEDs cathode. This is your soldering place.(melt the solder here).
Great all done! Now you have a 3x3 led square. Repeat this step two more times so you have three.
Lay those three LED squares on the table in front of you. now, i used some wire we discussed earlier to connect them all. On the squares there should be 9 anodes sticking up. You want to connect the anode of the first LED square to the corresponding anode one the second layer.
So, when your finished you should have 9 columns of anodes.
Then you need to solder you some wires going from the negative connections of all three layers. You should end up with three separate wires coming from the negatives(the cathodes).