Having dealt with the patent weenies recently, I would bet that there is not a patent limiting anyone from installing a hard case around a LiPo.
Give me a break, it's been done in almost every industry out there that has removable cells. They might be able to patent the connectors and integrated balance port but that's it.
It doesn't take much to vac form a lexan case that will strap in the car. Lexan must be fine it's what they use on the 3200 "hard case".
Just vacform one out that will fit more than one manufacturer's cells and you're done.