I'm not sure I understand the question. I don't think I've ever heard of a misting box being an actual box. The pictures I've seen have been more like a shower stall. The humidity in there should be fierce, and warp and otherwise demolish wood.

If you are new to propagation. a much bigger challenge than rooting the roses is getting them through their first winter. So you want to manage rooting the cuttings in such a way as to make it easiest to overwinter them. I root in the basement under lights at least partially because the rooted cuttings are going to spend the winter there.