etching on metal?

[momolo.livejournal.com]

i want to make pirate belts. i am going to buy some cotton web belts from the internet and stencil the ubiqitous skull n crossbones on them using acrylic paint mixed w/ textile medium.

however, i would like to purdy up the belt buckle. is there a relatively easy and cost-effective method of etching a design onto a nickle-plated belt buckle? or some other way to dress it up?

thanks!