I made a few little changes:
Combined the weapon mounts into the lower half of the body.
Added a little detail to some of the flatter areas on the lower body.
Added a "hex-pin" to align the top and bottom parts of the body.
Added "pin" or "ball joint" head attachment.
Added new hips with integrated pelvis armor.
Added new shoulder guns with support spine. I also flattened off the gun pivot so that it has a nice flat surface to print from.
Added new upper legs with a groove for the armor.
Added new upper leg armor with an index for the previously mentioned groove. I also made the upper leg armor a bit wider.
Added new lower leg with thicker ankle
Added new foot with thicker ankle
Added new right gun arm and shield. These have a male/female feature to help with gluing.
Added Gun Shields/Armor with "feet" to help them stay standing during the printing process.
Added gun arms that interface with the arm shields more.
Added pose-able gun arms. The gun arm can pivot up and down at the elbow for more dynamic poses.
I am done with this for now. Thanks to chris262 for posting the original model.
I did not make any changes to the original lower leg armor, so you will have to get that from the original source.