yea the grey i wasn't sure of until i saw this guys pic...the CLR shows alternating black and grey strips with black in the holes...i tried that and just couldn't do it..i am not skilled enough. the vocoder wasn't all the well defined shape-wise at the top so i couldn't see the lines well, made a few mistakes and had to go out a bit to even it all up.
I used the Humbol paints.
I used this guys as a guide.
http://forum.specops501st.com/index.php?/topic/2523-magma-trooper-specialist-application-pics/