I like the idea of using 3D printed covers to get the detail on the road wheels, but I wouldn't machine them out of aluminum, I would probably use stainless steel. The road wheels are unsprung weight so it really shouldn't hurt you if they're heavier and they won't be all that much heavier, but the stainless steel would wear and hold up much, much better than aluminum. Especially if you're using 6061. That stuff is soft as butter.