Stucco. You can paint over it but it'll never color match. Flat unpainted - sure - no biggie. Painted stucco is a bitch. It's like keying an entire side of a car (get an estimate on that sometime).

That's another reason the CyberTruck is kinda appealing to me (among many). A shorter wheelbase version could be nice, but I do have loads perfectly tailored the the first model's flat vault bed and size (drool drool).