Things You'll Need
Key mold halves
Having a back-up casting of your key can save you from locking yourself out of your home or car. Make a duplicate key without a locksmith by casting a copy with clay molding materials. It is cheap to copy any key with the right craft products. The process can be completed in under an hour. Copies are typically made with alloy slug, a cheap metal that dries and melts quickly.
Cut the brick of craft clay in half with a knife. You want both halves to be about equal. You should cut the clay in half along the length.
Exert pressure on the clay with your hands to warm it up. This is done by gently kneading the clay. Do not twist or break the clay.
Press the clay into the key casting mold. You will press the clay into the half that has two vertical pins. Press the clay until it is even with the surface of the mold. If there is excess, cut it off with the knife. Run a credit card over the surface to ensure the clay is completely flat against the surface of the mold.
Repeat step 3 on the other half of the key casting mold.
Dust the surface of both molds with talc powder. Blow off the powder that does not stick to the clay.
Set the mold half with the pins on a flat surface, with the pins facing up. Press the key into the clay. Press the other half of the mold on top of the key and properly align the vertical pins in the appropriate holes.
Place a heavy weight on the mold for about twenty seconds. For a weight, you can use a fifty-pound lifting weight or you can simply stand on the mold. Pull the mold apart and remove the key.
Casting the Key
Bind the mold together with two strong rubber bands.
Melt alloy slug in a ladle by holding it over a medium flame. After the metal has melted, leave the ladle over the flame for an additional thirty seconds. Warm the inside of the mold by holding it for five seconds over the flame.
Pour the casting into the mold. Tap the mold on the table a few times to make sure the metal covers all the small nooks. Wait thirty minutes for the cast to solidify.
Hold the mold vertically and pull the halves apart slowly. Lay both halves on a flat surface with the clay side facing up.
Insert a credit card under the casting and gently pry it loose.
Be careful not to accidentally pour the metal on your hands. Use gloves to protect your skin from the toxic materials.