An apparatus and method for forming a three-dimensional object within a block of transparent material by using a laser beam. This is useful in the field of rapid prototype manufacturing (RPM) in which a computer-generated CAD file defining an object may be converted directly to the described object. A CAD surface model is sliced and the data from the sliced model used as input to a numerically controlled machine. Because only the surface of the volume being cut from the solid block must be scanned by the laser beam, this process is much faster than other RPM manufacturing techniques where a laser beam must scan every point inside the shape being formed. Objects having complex geometries and/or hollow interiors may readily be formed using the disclosed apparatus and method.