Magnetism occurs at the subatomic level but can manifest itself on very large scales. Ferromagnetic materials, which include iron, cobalt and nickel, are materials that exhibit magnetic properties. The atoms in these materials are grouped in magnetically similar regions called domains. When the domains of a material align in the same way, the material itself produces a net magnetic field. Many kinds of nails, screws, tools and kitchen utensils are ferromagnetic. You can magnetize these and other ferromagnetic objects by exposing them to an existing magnetic field.
Stroke a magnet in one direction along your object in the area you wish to magnetize. This will align the domains of the material in the same direction.
Continue rubbing in the same direction, in the same area. Do not rub in the opposite direction. If you do, the domains will become misaligned and the object's own magnetic field will weaken.
Test the magnetic strength of your object on small metal items, such as paper clips. If the paper clips are attracted to your object, you have magnetized it.
Align your object so that is pointing along the north-south axis of the Earth. Use a compass if you do not know which direction this is.
Strike the object with a hammer repeatedly. This shakes the atoms out of their domains, causing them to realign to the Earth's magnetic field.
Test your new magnet by holding it near paper clips. If it is not strong, strike it again. In order to increase the strength of the magnetic field, you can also hold a strong magnet near your object while you strike it. The domains will then realign to this magnetic field instead of the Earth's.
As the strength of the magnetic field and length of an object's exposure to it increases, so does the amount by which the object becomes magnetized.