The Gundam’s Torso is nice and simple. The individual parts fit together easily, and the skirt armor is very flexible, so it won’t easily fall off when the legs are moved for posing (unlike the Zaku, which can’t help but lose its skirt armor when you so much as brush it with a finger).
… unfortunately, the waist is so simple, I don’t have anything else to say! Thankfully the next post will be much more interesting.