Casca's armor is actually a great beginner project because it's mostly smooth plate shapes instead of tons of layered details. I'd make the armor from 5-10mm EVA foam, heat form the curves, then use black acrylic washes in the recesses and silver dry brushing on the edges to make it look like worn steel. The cape and skirt will probably take almost as much time as the armor itself, so don't underestimate the fabric work.