Not sure about adding strength with paint but for chassis protector material (sheet plastic sticker material) check out TQRcracing. They sell it Ina sheet so you can cut to fit. Just look up any kit on their site, they'll list it as an optional part to that kit. -if your having a hard time finding it. I have used the material, not sure how much stength it will add. It does protect the chassis, but its not very rigid ...it may help?