Copyright laws do vary around the world... you cannot steal my car for any reason. That's not a copyright issue.

But I cannot prevent you from photographing my car in a public place. If it's a unique design, I can sometimes restrict you from publishing or making other commercial use of the photos.

In the US, it's legally considered "fair use" to make one copy of almost anything as long as the copy and the original remain in your possession. This includes music, magazine articles, and television programs. I don't know if copying a circuit has been tested in the courts, though.