Will Mr. Surfacer make smooth metal look cast?

You could take a wire toothbrush and lightly hammer the surface of the metal to stipple it - i.e.; use the end-on wires of the brush, and a hobby hammer to tap the brush.

I spray it with Testors Dullcoat. I especially do this with the chromed plastic that is supposed to represent cast aluminum.

For older cast iron I use another method- prime with Krylon primer, the grey stuff. Then I dry brush on some Testors "Steel". Just a little, to give it the slightest metallic sheen.

Why wouldn't it work on metal? It's simply a goopy coating that you texture by stippling with a nylon paint brush, like the cheap ones sold by Testors. It doesn't affect the underlying surface. It's a thickened, lacquer-based paint, so it should adhere fine, but you could always apply a metal primer first, if you want. Beware of actual lead alloys, though, because they can react chemically over time, producing so-called "lead disease," a corrosion that eats through paint and eventually destroys the part. Many museums ban white metal parts on display models because the alloys often contain lead, and are unstable over time. Good white metal alloys used for high quality miniatures are a cocktail of zinc, tin, bismuth and antimony, but contain no lead. Likewise, modern pewter contains no lead, but some antique period pieces do, as it was cheap. Gerald Owens