GLaDOS from Portal 2 isn’t an easy character to cosplay. People have done body suit interpretations that look cool, but cosplayer elliria wanted to create a true-to-game version of the computer system. She created the armor, harness, structure, and backdrop from scratch and wired the LED lighting. She got such a positive response to the costume and display that she created an AMA on Reddit to answer questions. The structure and harness was what she tested first:

The structure/harness were the first things I tackled on this costume, and I definitely fell out of it quite a few times while working out the best way to suspend myself xD I looked up extreme sports and theater harnesses to get ideas on how to go about doing it, but ended up with the final design mainly through trial and error (adding straps/padding, shifting the ropes along my body to find points that could comfortably support my weight, etc.). I’ve worked with PVC pipe for a lot of costumes in the past, and knew I wanted to use it for the structure since it’s so strong and lightweight, but I messed with the dimensions several times to keep it stable.
The main engineering aspect that stumped me was the top bar, which I can slide across in order to move my upper body side to side. I ended up using four caster wheels with a bar between the two sets to prevent them from sliding sideways off the pipe.

Read more at Reddit.