A fair amount of web searching and a small cash outlay left me with some mechanical drawings of an M2. I took these and machined out of 1/8" plate steel the pieces necessary to make a realistic full scale model. It looks pretty good! I thought about building a rotating turret system to mount on top of my roll bar, but decided that was a bit overboard. I also contemplated putting paint ball gun guts into it to make it a functional paint ball gun - again, I figured that would just get me into trouble. So, a simple mount was added to my roll bar to lift the gun above the windshield and keep it from banging me on the head as I drove. I don't have pictures of the build process, but here's some pictures of the final product.
I've also had a number of people, including cops, pull up behind me and pull out their phone-cameras to take pictures - all with big grins on their faces and many with a "thumbs-up". All that being said, I still won't drive into Chicago with this thing on! (but then, I won't take the Cobra into Chicago in the first place).