Just some pics to show my version of a grow rack using a system of pulleys and vinyl curtain (not unlike a window blind). Strip magnets help to seal the curtain to the rack and does a relatively good job or holding in the humidity. Any constructive comments are welcome. Pictures are not in any order. Sorry.
http://s960.photobucket.com/albums/ae90/sdav834/My grow rack/
http://s960.photobucket.com/albums/ae90/sdav834/My grow rack/