Step 1: Planning
After securing a supplier, I needed to determine just what and how much el wire I would need. I went with 4.0mm el wire for the main body and 2.2mm el wire for the glove details, both in 'Power Green'. You'll find that different suppliers stock different weights and colors of el wire, so it's worth doing the research to find exactly what you need.
This design required too much wire to be lit by a single battery pack that the performer could wear, which meant that I needed to cleverly design a lay out that would neither exceed the capacity of each battery pack, nor be disruptive to the designer's vision or the DJ's performance.
I started by roughly pinning out the design with yarn onto my old beat-up male dress form. By no means accurate, it was a good way for me to figure out which wires would connect, where to place battery packs, and how many I would need. Talking with the el wire supplier on the phone about the capacity of the different battery packs apropos the lengths of wire I would need was extremely helpful.