I worked from a concept that was provided for me. I modeled, textured, and rigged this guy myself. All images are rendered in UDK.
The basic idea is that it has 3 "tiers" that the player must fight against. The mech remains stationary in a large room, confined by scaffolding and such, as it is still not completely built. The room has several floors, and on each floor, the player would fight one tier of the boss.
As you can see, this guy is pretty large. This is a comparison of the mech next to some forklifts that are roughly human height.
There are several components on the body that open up to expose some glowy panels...these are the only weak points. Here are some examples of them.
These are some of the weapons that the mech uses to fight against you. On top, there is a large AA cannon, on the sides, there are 4 laser cannons with 2 diodes on each. There are also several smaller turrets scattered across the body.