Shipping LDs is a problem. When I get stuff from volume sellers they usually have a trick that involves using a relatively 12x12 box that is about 2" thick. The LDs are bubble-wrapped and then taped in such a way that they are suspended in the middle of the thickness of the box. It works pretty good for Recobancou, who have sent me dozens of LDs.
I recently had a guy from Switzerland mail me some rare anime LDs. They were just packed skin tight in cardboard with some of that thin foam/plastic stuff on the outside. I was worried when I saw the package, but amazingly nothing was broken.