Wires
There are various types of coil wire for building your e-cigarette's atomizer coils. Kanthal is most often used and is available as round kanthal A1 wire, flat kanthal, claptons, and even blends of different types of wire.
You can also choose between several types of non-resistive or less resistive wire if you wish to use your box's temperature control mode. Nickel, for example, has an impedance that increases when heated and this variation lets you calculate the coil's temperature at any moment.