Abstract: A method of replicating master molds used in the fabrication of microsystems having micron to millimeter sized features. Master molds are replicating using a polymer sheet, which is heated and melted onto an elastomeric mold fabricated from the master mold. The copy molds accurately replicate the geometries of the master mold, such as high aspect ratio features, microposts, and channels with slender sidewalls. The polymer sheet encases the elastomeric mold without the application of an external force, permitting copying without deformation of the features.