The Inventor

Play to your strengths. This gentleman is clearly into gadget building, and both his bracer and his pistol are the center of attention. A relatively unadorned costume keeps the focus where it should be: on the technological gadgets he's sporting.

The hat is a bowler. The most common color is black and I love that he's gone with something less traditional. King of matches his gadgets. Bowlers can be found all over the internet. Not sure where he got the goggles. Again...he decided to not go with a standard design.

I'm guessing by the collar that he ordered the shirt specifically as a costume piece. however, a collarless shirt or even a standard pointed collar dress shirt would work well here.

The suspenders are a nice touch, particularly since he got the kind that actually buttons to the trousers instead of clipping on.

I'm guessing he's wearing fairly standard dark pants and dress shoes, although obviously they didn't make it into the picture.