Thanks to everyone else's post here, I got some great ideas. We used two foam insulation boards and cut them down to 6' x 8'. We taped them in the center and covered it with batting. I used office supply clamps to make it taut and secure. It is suspended from the ceiling beams (sewing area is in my basement). When I don't need it and want the view from the windows, I can just fold it, lift it up and attach the entire wall to the ceiling so it is completely out of the way. He used large clamps to hold the wall in suspension so it is completely portable - if I want to take it down and move it to another room, it's very easy. Nothing fancy (neither is my sewing room) but it sure serves its purpose.
entire wall suspended from ceiling