Please note that this is a beginner project, and that I am just learning to solder and wire myself.
The wiring here is fairly simple, but it takes some thinking to figure out, especially without an equally confusing diagram...
It's amazing how much I'm getting flamed for such a simple project. I fully acknowledge that it was possible for me to use a bigger battery with a resistor, however I did not have a resistor with the appropriate ohm value at the time for any of the batteries I had present. Not to mention this is a beginner project, and the button cells work fine, even with a sequence of three LEDs. To go even farther, the maximum voltage for the green LEDs is exactly 3v. A 1ohm resistor would be useless here. The maximum voltage for the yellow is slightly less than 3v, but enough that they've been left on for more than a couple days combined, and are doing just fine.
Step 1: Materials
Wire - Any scrap will do, just make sure you have enough, it is extremely helpful if you have two colors
PC board - I got mine at RadioShack, they're cheap
Six LEDs - Three one color, and three another. All should be low enough voltage to be powered by 3-4 volts. (two 1.5-ish button cells)
Two switches - One 1-way and another 2-way
Two 1.5V Button cell batteries - Power
Multimeter - Optional, helps test connections