In days of yor, when the Three Musqueteers rode. iron shooting crutches were standard. They went out of style when muskets got lighter and had bayonets to fix. The problem I see is that an iron crutch would be too wobbly, as opposed to cross sticks forming a stable triangle. I think that a blacksmith could run one up in a jiffy, but that you will be using it for toasting marshmallows for a loong time