I happen to have three windows in my sewing room, which is at the north side of my house. I had my husband cut me a piece of solid insulation board the size of the inner part of the window, which is about 58" by 58". I then put up a curtain rod, sewed a pocket onto 2 pieces of white flannel, which I had sewn together vertically and hung the flannel so that it is quite flat from the rod. It works great for me and with the solid insulation, I am able to pin right into it when necessary.