Hmm...sounds like you'll need sheets of styrene to make yourself a costume. You could use cardboard if you don't want to go the styrene route. Check out some anime cosplay sites for tips on working with styrene.
And you'll likely need some makeup...to give the human half face some "techno-cyborg" details...
Hey, what about a costume based on this:
You'll have to learn how to ride a unicycle, your face will appear through the plastic "screen" and you have unlimited range of motion in your arms!