A method for producing a cast article comprises using a porous powder article as a sacrificial pattern. The porous powder article is preferably made using a rapid prototyping process. The porous powder article is used as a sacrificial pattern for a mold into which a molten metal is cast. Some embodiments include a step of proving the porous powder article with a ceramic coating. Methods of making molds and patterns using a porous powder article are also disclosed. The powder comprising the porous powder article may be a metal, ceramic or cermet. In some embodiments, the powder alloys with the molten casting metal. In some other embodiments, the powder and the casting metal form a composite. Sacrificial casting mold patterns comprising porous powder articles and casting molds comprising such sacrificial patterns are also disclosed.