a couple of years ago my nephew and I built a wood fired forge, using materials that were handy, it went together fairly easily, and works fairly well, we never got it hot enough to forge weld, but the flip side of that is you don't burn the carbon out of you iron if you leave it in too long, my favorite thing is the lack of toxic smoke. we used aspen, I know not even remotely the best wood for heat, but it is clean.