1. This microscope costs less than a dollar to make

[Image from PLOS journal]
Manu Prakash and Jim Cybulski created a foldable microscope in 2014 that was made mostly of paper and had a cost of goods of less than a dollar. By December 2015, they founded Foldscope Instruments to scale up production of the microscope while releasing other inexpensive scientific tools.
The Foldscope was designed by combining the principles of optical design with origami. Recent advances in micro-optics and flat manufacturing are used for large-scale production of the microscope, according to a 2014 PLOS journal article about it.
It is an origami-based optical microscope that can be built from a flat sheet of paper in under 10 minutes. It has over 2,000 times magnification with submicron resolution and weighs less than two nickels. It is also small enough to fit in a pocket and doesn’t use any external power. Durability tests have shown that it can survive being dropped from a three-story building and being stepped on by a person.
To use the Foldscope, users insert a sample mounted on a microscopic slide and turn on the LED. Samples can be viewed while panning and focusing using their thumbs. Users can view the sample by putting their eye close enough to touch their eyebrow to the paper and looking into the micro lens.