This is my lock for my locker at work. All I did was buy a regular Master padlock (I got mine with a purple dial) from Target for about $4 and decorated it with some old nail polish.
It makes it so you can have a unique lock!!
(I used a metallic pink to accent the purple and then used glitter flakes over that)

There is absolutely no practical use reason to do this, it's just fun. :)