Catholic nuns are recognisable around the world; especially when they wear black and white habits and veils. Many nuns make their own habits and with some ingenuity and a stretchy white headband you can make your own as well. Nuns are supposed to be modest and frugal, so your nun's veil won't be made with complicated stitching or expensive fabrics. You may even be able to make this veil with things you already have around the house.
Measure the circumference of the white headband. The white headband will serve as the coif, the piece that goes around your head and holds your veil in place.
Cut out a square of black polyester. The width of the square should match the circumference of your headband and the length should be about 2 feet.
Pin one end of the width of the black square to the inside of the white headband. The black polyester should fit along the headband's circumference exactly. Make sure that the polyester is pinned evenly.
Stitch the polyester into the white headband with your needle and thread. Make sure not to pull or stretch the headband while you are stitching.
Leave the seam between the two edges of polyester open. This will allow the fabric to lie flat against your back. Put the headband on your head as you normally would. You should now have a black veil covering your hair.
Pair your homemade veil with an old graduation gown for a complete costume.