Lost planet themed (second one maybe?)
 

a Famas fashioned after their machine guns is something i have been tempted to try, but there are not too many available...

here are the 3 variations!
http://images2.wikia.nocookie.net/__...achine_Gun.jpg
http://images4.wikia.nocookie.net/__...hinegun_II.jpg
http://images2.wikia.nocookie.net/__...hinegun_SP.jpg

and obviously do it in full metal :)