Having spent most of the day at an excellent camera club printing training session (provided by one of the big paper-and-ink companies), I almost ended up blipless (shock, horror!).
So I looked around for something to experiment on in my study and spotted a transparent CD case lying around. I reckoned it would probably make some pretty patterns if illuminated from behind with polarised light and photographed through a polarising filter. I wasn't disappointed. Blip sorted!
(For this kind of shot I usually just use my computer screen as a convenient source of polarised light, with it set to fill the screen with a pure white "picture". You don't need a fancy polarised light box.)