A toy, art object, decoration, ornament, entertainment device, advertising device, paperweight, or other device is made of a soft deformable plastic material in shapes of prisms, lenses, wedges, cubes, pyramids, as well as other forms that display the changing stress patterns formed by deformations of the photoelastic material. Magnets embedded in the material apply forces that create new patterns. Polarizing films within, or covering the clear plastic enhance the viewing effects. External forces, such as manual manipulation, springs, strings, elastic bands, clamps and other devices are used to create interesting optical effects. The viewing effects increase the entertainment and aesthetic value of the devices.