Ooooh what fun!  I love this sort of thing and wanna thank BB for taking the time to show the math and figure this stuff out.  I've grabbed this entire thread and will go over it in detail at work tomorrow while my computer renders more boring technical video.  My personal project at home involves creating sheer organza-like materials for designing bridal apparel.  Some of the new real world materials being used by a couple of designers in eastern Europe have some interesting sheens.

...and thanks for dragging me over here Boni.  I'd've never found it on my own.  BG is correct in saying that the forum's search engine is horrific.