I am the GLaDOS cosplayer from PAX Prime, suspended upside-down from a structure. I made the entire costume from scratch. AMA!
Here's my proof.
I've been cosplaying since 2008 and been an avid gamer for quite a bit longer. I'm currently at university for computer science/game design, so cosplay fits right in with my other passions. I've had the idea for an entirely faithful GLaDOS cosplay for a few years now, and finally decided I had honed my sewing and armor-making skills enough to tackle it. I built the structure/environment, constructed the armor, sewed and made the harness, painted the backdrop, and wired up all of the lighting - anything for accuracy!
(Edit) Whew, thank you for asking such varied and interesting questions, I really enjoyed chatting with you guys! I'm heading off to bed but I'll check back in the morning if you still have something pressing to ask.