Paul,

You have to reach your own conclusion about the ethics. You've seen some arguments on both sides.

None of us has identified himself as an attorney. But, IMO, in the US, I don't think you can find any examples of somebody getting into legal trouble making one copy of a design, who didn't try to publish or sell it.

If your creation involves violating another law, (such as the DMCA), then that's another matter.

After examining the ethics, you might also consider whether, by making an exact copy, you'll miss an opportunity to learn something.

regards,
Mike