For the eyes and mouth, I used some metal forming mesh sandwiched between super sculpey. This gave a little depth to eyes and mouth, as well as contributing to the "mechanical" feel. I added some random scorch marks to simulate battle damage.
I kept the rear simple, except for the wingpack. I wanted something on the back of the figure to suggest flight capability, and came up with the winged jetpack you see here. I'm not as happy with it as I hought I would be, mainly because by this time I was losing steam on the project and just wanted to get it finished. That's why I skipped adding a lot of detail to the wings to make it look more metallic and less like a pair of silver painted cardboard wings the likes of which I used to play with as a kid.
Oh well.