You can transform most any paintable object into something resembling an artifact from the Old World. I purchased a pair of terra cotta candlesticks and a plaster plaque from an import store and rusted them using art store supplies.

You will need two disposable paintbrushes, a bottle of Instant Iron and one of Instant Rust. Following the directions on the bottle, paint on the Instant Iron (ground iron in a water base medium). Allow each coat to cure overnight. Paint on as many coats as needed to cover. Paint on Instant Rust. Allow to dry before applying a second coat. Add additional coats until you achieve your desired finish.