When your eyesight blurs, the local optician can whip up a set of lenses quickly. But in rural areas of developing countries, corrective lenses are hard to come by. MIT instructor Saul Griffith has designed a solution: a briefcase-sized kit that uses an ordinary kitchen appliance to make spectacles to spec. “Essentially, it’s an orange press that can print lenses in the field at extremely low cost,” Griffith says. The kit uses standard safety glasses, costing less than a dollar, which are coated with an epoxy. The press imprints a prescription set of light-focusing concentric ridges. In minutes, out pops a flat Fresnel lens akin to those used in stoplights (photo). Students from Harvard Business School are working on distributing the lensmaker where it is most needed.