Take the leather shapes to your workspace. Soak the face and back of the leather with the spray bottle of water. Keep the pieces wet while working with them. Lay the leather triangles face up with the skinny, rounded tips pointing outward. Fold the triangles in half (face-to-face) as shown on the left side of this image. Hammer along this seam to create a crease in the leather.
About one-third of the way up the ear from the base, create another angled seam on both ears as shown. Hammer along this new seam.
Open the leather back up. Take the top half of each triangle and fold it behind the piece. The leather should roll behind the piece very easily. Adjust the width of the rolls so that the raised rolls are wide at the base and narrow at the point of the ear. Create a cartilage ridge with each roll by pushing down on the leather with your fingers to flatten them and make them look more natural. Roll the bottom edges of the ears (the halves you haven't done anything with) under the rest of the ear, as shown on the right side of the image. Make the outer edges of the ears by adjusting the width of each ear so that they are wide at the base and narrow at the tip. Make sure that you keep the base pockets of the ears wide enough to fit your own ear inside of them. When the ears look good, firmly press along the new edge with your fingers to define the shape.
If you want some extra detail, pinch areas on the left side of the ear to create cartilage ridges near the base or tip of the ear.
Allow the ears to dry. When completely dry, flip them over to the back seams. Trim the overlapping leather so that the pieces only overlap about 1/3 of an inch. Take the contact cement and apply it to the narrow flap, then adhere the larger flap (which goes under it) by firmly pushing them together. Hold the pieces in place by hand for a few minutes until the cement begins to bond them. Allow the cement to cure for 48 hours.
To finish the ears, cut a curve out of the back of the base of the ear that is slightly larger than a quarter. Put the ear on your own and adjust the cutout by trimming the shape to fit the back of your ear. Be sure to clip the corners so they won't poke you. Also cut away the outer edge of the cartilage to fit your ear by cutting 3/4" up the outer edge, and round off the outer bottom edge of the cartilage roll. For a nicer finish, trim 3/4" from the base of the front of the ear and up the hammer seam. Moisten the bottom of the ear with water and fold the base of it up into the inner pocket. This will create a slightly more realistic appearance when worn. When completely dry, you may paint your finished ear with acrylics to match your skin tone. You can also add assorted chains and jewelry to customize your ears.
Now you can glue the ears onto a headband, making sure that they are in place so that they will cup your ears, or just poke them through the inside of a wig and fit the bases over your ears. Have fun wearing these for parties, events, shopping center raids or whatever you'd like!