Apart from the box, you'll need:
1x DPDT switch, rated for mains voltage.
1x 220-12V transformer.
2x 3300microF polarised caps, rated for 25Volts or more.
2x 12V fans
1x bridge rectifier, or 4x power diodes.
1x three-prong socket like the one that computers use.
Lots of wire.
Screws, bolts, nuts.
Drill with metal bit.
Clear pieces of plastic for gluing over the openings of the box.