FoldScope is microscope that can be assembled from a flat sheet of paper. It costs less than a dollar to produce, can provide over 2000x magnification, and requires no external power. The tool aims to help diagnose diseases in developing countries and to make science education easily accessible to people around the world.
This is a little outside my expertise, but man this is cool. These are the types of things that change the world. These are the types of things we should want to design. It costs less than a dollar to make and it is going to save thousands of lives as well as educate thousands more.