Want to be your own locksmith? You can now. Hack A Day has an easy accurate way to make your own spare keys with nothing but some plaster, sun and a giant fresnel lens.

First, you put a thick layer of plaster of paris in a small box, and place the key halfway into the surface. Then fill the rest with plaster and let it dry for a few hours. After that, place a bowl of zinc pellets beneath a fresnel lens to give it some molten metal.

After that, capture the sun's rays for some heat. After they are melted, you can pour into your key mold, and allow the zinc to cool and use your keys after that!

Check it out after the jump: [Hack A Day]