Courses: P14, P16, P41, P47
A variety of birefringent plastic objects. Place a piece of polarizing film on a light box. Set the plastic item on top, and then add a second polarizing film at 90 degrees to the first one.
The "crystal" is simply a crumpled up piece of plastic transparency set in a box with polarizers all around.
We have a small amount of material that will show stress and strain when placed between two polarizers, but it takes a lot of force to see much effect, and the pieces end up quickly broken.
