The present invention provides fabrication methods using sacrificial materials comprising polymers. In some embodiments, the polymer may be treated to alter its solubility with respect to at least one solvent (e.g., aqueous solution) used in the fabrication process. The preparation of the sacrificial materials is rapid and simple, and dissolution of the sacrificial material can be carried out in mild environments. Sacrificial materials of the present invention may be useful for surface micromachining, bulk micromachining, and other microfabrication processes in which a sacrificial layer is employed for producing a selected and corresponding physical structure.