For a change of pace, I thought I'd do a full-on how-to post here. The technique is loosely based on the faux-metallic surface technique that Rheni Tauchid demonstrates in her book, The New Acrylics. (If you're an acrylic artist, do yourself a favour and pick it up; it'll change your life.) I'm going for a different look than what's shown in the book, though, so the shopping list is a little different.
What you'll need to replicate what I'm doing here:
Surface prep and texture media:
molding paste or super heavy gesso
iridescent stainless steel
phthalo blue (red shade)
transparent red oxide
serrated painting knife (or fork)
paper towel or a rag
Okay, for the first step I start by prepping the surface (in this case it's masonite, but it could easily be canvas or wood) with black gesso. Once that's dry, I use the serrated knife to apply molding paste. I'm not concerned with getting an even coat; the more chromatic variation you have with this technique, the better. And there are any number of methods you could use here to create the texture - this just happens to be one I particularly like.
Step two is the initial colour application (after the molding paste has dried, obviously). A few uneven washes of transparent sepia give the surface a surprising amount of colour variation. I try not to go too heavy with the sepia because ultimately this will have a blue cast, but don't hesitate to experiment.
For step three, once the sepia washes have dried, I lightly drybrush some iridescent stainless steel. This is the core of the metallic appearance. Go lightly with the brush - ideally the only stainless steel will be on the raised parts of the surface.
Step four builds on this - I'm randomly adding interference violet and orange. You might also consider using one of these at the top of the metallic area, and the other at the bottom. Again, the possibilities are pretty much limitless.
In step five, I'm adding more interference colours after the violet and orange have dried - blue and green, specifically. The result of these two steps is a surface which shows an almost impressionistic range of colour, depending on the viewing angle.
Next comes step six - washes of the phthalo blue. These are applied much like the sepia was - layer upon layer of partial coverage, overlapping frequently. Allow each wash to dry completely before you add the next.
In step seven, I'm adding splashes and splatters of the blue again. I went with a lot of dribbles of paint across the surface to create a sense of motion, but of course this approach is optional.
Once you've built up a few layers, you're ready for step eight - rust. I rub bits of transparent red oxide on with a bit of wet paper towel. Some of the paint is catching on the raised parts of the surface, and some of it is getting pushed into the crevices. The water in the paper towel also adds to the randomness.
In step nine I'm adding more streaks of phthalo blue. I prop the righthand side of the masonite up, and add the blue so it flows across the surface. Here's the finished result:
Viewing from different angles will reveal different colours. That's really the key to this whole method. Give it a try for yourself.