I started by taking the main design by Chris P. seen here, then I changed a few things here and there to make it more accurate. I think it turnned out good, the only thing I don't like is that it is as tall as a minifig, it should be shorter, oh well.
Ok kids, now for story time! Once upon a time a little Grunt was skipping around the Covanant base.
Suddenly, an strange green object rolls in front of him.
The Grunt eagerly picked it up and said, (In whatever language Grunts speak) "I must show this strange object to my superiors, I could get promoted to spec ops!"
Ka-BOOM! and Voila, instructions. (Which I know most of you don't need) The End, you gotta love happy endings.