Lighting newbie question: I know that calculating the size of anything in electronics can get pretty complicated, but would it be a safe assumption to say that if you're working with LEDs and a 9V power supply that 22 gauge wire is a pretty good all-around wire choice?

Good question.

Here a site with a formula and table. (http://www.powerstream.com/Wire_Size.htm)

I think what we're doing is chassis wiring (unless you're talking about the length of wire from an external power supply). 22 gauge is good up to 7 amps for chassis application. A single LED is 0.020 amps or 20milliamps so 22 gauge is more than sufficient for a whole lot of LEDs.

Consider using magnet wire (http://www.radioshack.com/product/index.jsp?productId=2036277) inside the model. It's easier to work with and great for small channels etc. The thinnest 30 gauge wire in the set I linked to is good for 0.86 amps or a lot of LEDs (as few as 40 depending on your circuit). Magnet wire is coated with enamel for insulation that scrapes off easily with some sand paper or a knife for soldering.

Thank you, Steve. That was VERY helpful.