Taroboard is a wonderful thing.  All cels should 
be shipped with this stuff.  It doesn't bend 
easily at all, and it makes for a nice, small 
package when shipping.  The worst I've ever seen 
is a slightly bent corner. ^_^

And it has other uses too- I save it and use it 
as a lap desk sometimes when I want to draw or 
write while lying down. Plus you can reuse it 
when shipping/transporting your own cels, for 
whatever reason.

(This commercial brought to you by someone who's 
bought far too much from Anime Taro... ^^;)