Scanning capacitance microscopy is a new mechanically scanned microscopy. In its present configuration, the microscope has a demonstrated capability of detecting variations in surface topography of the order of 0.3 nm over areas of the order of 0.5 &mgr;m2. This great sensitivity to height changes is achieved by the placement of a capacitance probe some 20 nm above the sample surface. This paper describes the construction of the microscope and discusses its use in relating surface roughness of plastic parts to mold finish and material property variations.