Thanks man! This build has been mothballed for the time being. I got the Iron Man bug and decided to see if I could knock out a MK III. This time I've given myself 10 months instead of the 30 days I gave myself with TDK. It's going good so far.
I'm working on a similar project to this myself. Wondering if you have any advice for securing the cardboard armor pieces, i.e. joining all the chest pieces together, abs, etc in a secure and wearable way?
Shoulder belts look good. I think you should switch from corrugated card board to a plain thick 400gsm board or something lighter and then used corrugated card board to strengthen your build.