How to make a 3 season single mummy sleeping bag liner?

1,Spread the material on the floor in front of you. Using your 3 season mummy sleeping bag as a guide by laying it on top of the fabric, trace an outline around the bag.
2,Cut one side of the pattern out. Leave the other side attached. Fold the cut side over to use as a guide and cut around it.
3,Place both sides together but inside out. Pin the edges,
4,Sew the bag up, leaving an area free where the zipper should go. As you get closer to this spot, stop and pin the zipper into place.
5,Turn the 3 season single sleeping bag right side out. Cut the area out where your head will go, right above your shoulders. Your liner is now ready to be used.