You can span a role of reflective film from the ceiling to the floor using staples on the ceiling and role length of 1”x1” wood or PVC pipe in the bottom and tape it, to hold the film stable. You can also use insulate sheets of foam. You can run a strip of 1”x1” wood on the ceiling and floor, and then tie the sheets to it. If you are trying to build a whole room, look into the grow tents. I recommend using the Secret Jardin’s, Mammoth, or the Grow Lab.