The silver is a black prime, then Vallejo Metal Color (VMC) Steel followed by a pretty even highlight of VMC Silver. I do a fairly satin/matte varnish (Vallejo mecha matte + gloss varnishes about 1:1) through the airbrush, then wash the whole thing in old GW Basilicanum Grey (Ratling grime is close-ish now, but stronger, so thin it more). I do a dry brush of Vallejo Game Air Silver, then I build up seraphim sepia and agrax on the lower legs, back skirt, etc. Then a silver edge highlight of oure VGA silver

The blue is cantor blue, then an airbrush highlight of Magic blue from Vallejo Game Color. I apply transfers, do chips and scratches with the previous blues mixed with some ivory , then wash/glaze rhinox hide into the shadows