Roll-up window shades come in certain widths x heights, 180x210 cm, 120x160 cm, etc. They are made of some kind of fabric rolled up in an aluminum tube.
To adjust their width to fit your window frame you probable have to saw the aluminum tube and cut the fabric.
The biggest challenge is to make a straight cut, without releasing the fabric from the tube. It's even more difficult when it's a double layered plastic drape
Are there any tips in how to make the perfect cut for this kind of shade?