How can I make a Taco Shell?
No mold required! 

Simply heat about an inch of oil in a frying pan (less oil if you're making less shells - this is enough for about a dozen), then cook small, flat corn tortillas one at a time. 

Cook for about 15 seconds on each side. Once you see bubbles on the tortilla, you're all done if you like soft shells. 

If you like more crispy shells, go ahead and fold the tortilla in half, and continue to cook. Keep flipping it over so you don't get it too browned on either side. 

You can blot the tortilla with paper towels if you'd like. 

Similar topic - you can make your own shell for taco salad by placing a large flour (burrito-size) tortilla in an oven-safe bowl (shaped however you'd like) and putting a big ball of tinfoil inside it. You can also do the opposite - place the bowl upside-down and drape the tortilla over it. Either way, Bake at 350 degrees for 10-15 minutes until it's lightly browned, and you're done! When you remove the tinfoil and the bowl, the tortilla will hold its own shape.