Some of the LV boxes come with a stiff brown cardboard that is removal. I've used that before as a base shaper and it's perfect.
Others have suggested opening a CD case and leaving it flat on the bottom. I've used that before as well and it works too.
I'm new to this forum and I've just seen your photo of your purse collection. WOW. Very nice!!
I'm considering buying Speedy next - so this thread is very informative.