PS: If you're doing a rough cast, get one of these. Buy several 5-packs of fine-grit sanding tubes. You will destroy the contour sanding pad (black and yellow things) within minutes sanding on metal, so stick to the jigs and sanding tubes.

This thing probably saved me 10 hours, and lots of blisters. It costs $80 with extra sanding tubes. A worthwhile investment if you ask me.

Dremel Contour Sander: