The range of aspheres that may be designed is larger than the range of aspheres that may be successfully measured and manufactured. This can lead to frustration for both the optical designer and the optical fabricator. Available polishing tools impose some limitations; full-aperture interferometry imposes other limitations. The optical designer must include constraints in the merit function to encourage the design to respect these limitations if manufacturing is to proceed smoothly. The aspheric surface curvature plot provides key information to understanding which constraints must be added to the merit function to encourage the asphere designs to stay within the portion of solution-space that may be manufactured and measured. There is often little or no performance penalty due to adding these constraints.