Does it have to be a rigid shell? David Regal has his "throw away" deck available that looks like a deck that can be wadded up and tossed away. Maybe you can use his pattern and put it over something like Chazpro's deck shell form in place of the card box pattern they use.
The effect that I have in mind would require a rigid shell of a deck of cards. While I continue to try and find the right shell of a deck of playing cards, I'll look into possibly buying the David Regal Disposable card effect as suggested. Once I get one, I'll try to apply it to the desired effect I want to perform, and who knows, it might just work as well as a rigid shell of cards. But if anyone happens to run across a place or know someone where I can get a rigid card pack shell, I would be eternally grateful for the help.
Also, if you're curious about what I'm trying to accomplish, send me a PM, but I won't go into details about the effect I want to use it for, unless you too, own the effect.