I'm sorry to start a new thread for this post, but 
for some reason there's a whole little segment of 
posts that I can't seem to get the "answer this 
post" button on, and yours was one of them.  (Also 
for some reason I can only see your original post 
in the "latest entries" listing rather than when 
looking at the full cels forum list.  Very odd.)

Anyway, my solution for keeping cel layers 
separated but still visible was to buy a bunch of 
cheap (polypropylene) cel bags and cut them up to 
insert between the layers.  Then the whole 
sandwich goes inside another cel bag.

If you need a source for cel bags, try searching 
the most recent forum archive for posts by "oion".  
She listed a bunch of URLs of places that sell 
bags.  I got mine from Dandl (http://
www.dandlproducts.com/), but they have a $40 
minimum order the first time you use