UniqueAndAmazing I know but it's an awfully difficult way of doing it, my lecturer (who is a technical GENIUS BTW) said don't bother and I never have. So far the most I've been off is about 1 mil which he told me was crap and to do it again
. I luf him though, platonically, if you're reading this Bruce don't get scared 
I did a fly zip in my year 2 collection, it took me a day to work out mostly sat with my jeans open looking at the zip. Much respect for those guys who had only 7 hours to do a whole pair of trousers!
LookingForwardToMyThirdYearTiggaxx