It is likely that the coming decade will see the development of a large visible light telescope with enabling technology for imaging exosolar Earthlike planets in the habitable zone of nearby stars. One such technol-ogy utilizes an external occulter, a satellite flying far from the telescope and employing a large screen, or starshade, to suppress the incoming starlight sufficiently for detecting and characterizing exoplanets. This trades the added complexity of building the precisely shaped starshade and flying it in formation against simplifications in the telescope since extremely precise wavefront control is no longer necessary. In this pa- per we present the results of our project to design, manufacture, and measure a prototype occulter petal as part of NASA's first Technology Development for Exoplanet Missions program. We describe the mechani- cal design of the starshade and petal, the precision manufacturing tolerances, and the metrology approach. We demonstrate that the prototype petal meets the requirements and is consistent with a full-size occulter achieving better than 10-10 contrast.