The thing that distinguishes a Steampunk costume from a Goth or Vampire costume is the GEAR. Here are the essentials.

Weaponry

In the past that never was, it was a very dangerous place. Or, so you would imagine considering the wide array of weaponry. Here is a How-To to make a Steampunk Gun from a Nerf Gun:

• How To Make A Kick Ass Steampunk Nerf Gun

Here is my How-To to make a Brass Ray Gun:

• Pick Me! » How To: Steampunk Brass Ray Gun

Here are ideas for more steampunk weaponry:

Goggles

For some reason, goggles (or strange eyeglasses) seem to the MOST important feature of a good Steampunk costume. Here is a slideshow from Flickr showing TONS of ideas for goggles:

An Embellished Top Hat

It’s not enough to have a top hat. It has to be embellished in some manner. The easiest way to make your top hat steampunk is to put your goggles on it. Then you don’t have to wear the goggles on your face for the whole party (hot and hides your eyes).

Boots

You don’t necessarily need combat boots, but they seem to be a favorite. Spats also help complete the look.

Gears

Gear embellishments are the best way to distinguish yourself as Steampunk aristocracy. Here are some ideas for jewelry, clothing and other gear embedded jewelry.

Cameo Jewelry

For the ladies, it’s always nice to have some sort of cameo jewelry.

I especially like my mourning pin from my grandma’s collection of “junk” jewelry. It was perfect for my costume.

With just a few additions, you can make a boring Victorian costume into a Steampunk costume. Have fun!