Hi!  I just got my first harmony cel in a few 
weeks ago as a gift, since I've had a tiny bit of 
a crummy year.  Sadly, I dont have a scan >_<.  I 
have also been very curious about them, I was 
really taken aback when I got it in.  The bg is 
completely colored and shaded on mine, it looks 
like a real watercolor painting.  Then, there's 
acetate for the lines on the characters.  Then, a 
third layer for the airbrushing effects. Mine is 
normal sized.  I think most are normal sized, 
I've never seen an oversized one yet.  They're 
really great tho, and one of a kind!  If you ever 
see one up for sale, I highly recommend grabing 
it.