I had a grandfather with patents, a brother with patents, and another brother seeking them. I have seen the time, sweat, money involved with getting them so this is my philosophy, "If in doubt, don't." I don't know how much patents differ from copyrights, but they have worked hard to earn their status as a patent holder. I would rather err on the side of seeking permission, when it maybe isn't necessary, than to steal someone's labor of love and profit.