What are the ingredients for a taco shell?

If you're making your own, it's typically masa harina, which is a flour made from corn, and water. You can find masa in most grocery stores with an ethnic section. Aldi's also carries it.

Mix enough water into your masa to form a dough. Pat it out as thin as you can, or you may be able to find a tortilla press to help with this part. Fry the patty in oil until crisp. Remove from the oil and drape over a rack to form the shape. I find an oven rack sitting on a couple of glasses works well.

You can also buy corn tortillas and fry and form those as above. For a healthier version, spray corn tortillas with a little vegetable oil and drape over your oven rack. Bake at 425 degrees for about 15-20 minutes.