The Nisse is a fantastic sniper option. MSV (MultiSpectral Visor) Level 2 means he's not taking the penalty from Camouflage, Mimetism, ODD or TO Camo, and his own Mimetism and ARM 3 makes him fairly survivable. I can't wait until they release an updated HMG version.
The black and the silver were painted using the same paints. It's just that for the silver, the lighter colors take up more area than they do on the black areas, where they are just edge highlights.
Base coat with black, then highlight with VMC 168 Black Grey, 166 Dark Grey, 160 Neutral Grey, 155 Light Grey, and White.
Tones are added to the silver parts with VGC Turquoise and P3 Cygnar Blue Base.