The main lines were simply the pen tool, as was the webbing--I'm not sure I really succeeded in showing the tension on the webbing as it went over the curved surface of the envelope. The netting at the top is just a crosshatch pattern fill.

Again, thanks for the compliments. Hopefully I'll continue getting projects that lend themselves to cartography. I should probably be careful not to pigeonhole myself too much, though, or the only job I'll be able to get upon graduation is as an expansimator for National Geographic's website.