Depending on the angle at which you look at a set of venetian blinds, there is a variation in the width of the gap/lath angle.Op Art Venetians take advantage of this simple phenomena.
The Op Art idea consists of two sets of blinds with narrower, closer spaced laths, placed one directly in front of the other. Each is of the same drop length, but one set has a lath less. This means that an infinite number of subtle patterns can be created by varying the pitch of the two blinds.-- xenzag, Nov 30 2007 Moire fringes http://en.wikipedia.../Moir%C3%A9_patternBoth useful and aesthetically pleasing. [8th of 7, Dec 03 2007] + and a couple of sexy Venetians to open and close the blinds for me!-- xandram, Nov 30 2007 Nice-- hippo, Nov 30 2007 If you add the capability to tilt one set with respect to the other, you can have Moire fringes ....-- 8th of 7, Dec 03 2007 Now you get the picture... though I wasn't certain that this would create real moirés so I didn't use that term.-- xenzag, Dec 03 2007 Can you "create" moiré fringes or are they merely an artefact of observation ... ?-- 8th of 7, Dec 03 2007 with thick acrylic n reflective coating you could make periscopes-- beanangel, Dec 05 2007 random, halfbakery