I have a few dougas and cels that I would like to 
bring to a convention and possibly have them 
signed.

I read once that it may be a good idea to have a 
blank sheet of acetate over each cel/douga for 
convention guests to sign on, because:

[1] they can sign over the cel's or douga's image 
(particulary when the image takes up most of the 
space already) without worry, and ...

[2] I could allow the ink to set on the blank 
sheet separately without worrying that it might 
stick to the cel bag or that it might bleed a 
little.

So I'm looking for a place online or near Los 
Angeles that I get find blank acetate sheets.  I 
also would like to know who is this material 
usually sold (in large sheets? in packets that 
are cel size?) so I can figure how much to buy, 
if I have to cut them up myself, etc.  And how 
much does it usually sell for, too?

Also, if there is a better material than acetate 
for the purpose I have in mind, I'm open to those 
suggestions as well.

Thanks!