A Stanford researcher, Manu Prakash, has developed a 50-cent paper microscope capable of 2000x magnification. His interest was chiefly in making an instrument for diagnosing blood-borne diseases like malaria. However, the microscope has many other potential applications including basic science education.
An article in Scope, published by Stanford Medicine, describes the origami-like construction and use of the little microscope, and includes this Youtube video:
The web site for the project includes a request for 10,000 volunteers to beta test the Foldscope and to help in developing an open-source manual for the instrument.