Smartphone microscope attachment based on the model provided by the Pacific Northwest National Laboratories (slight modifications to meet minimum wall thickness).
3mm glass bead must be obtained separately!
The microscope works with a glass bead placed in the circular hole, which provides a 100X magnification. Please read the original article in http://availabletechnologies.pnnl.gov/technology.asp?id=393 for more information and a list of places where beads can be purchased. A sampler of beads for this purpose can be purchased at BioSpec.
The markup for the modifications I made is only 50 cents. Microscopy rules!