The Crossroads of the Aether
My first inclination was to suggest the one item no Steampunk can be without. Goggles. But that may be something you already thought of.
My next thought is this. As part of your personae...what little item would you character NEED to move himself further along the line? So first describe to yourself what sort of fellow you are and go with that.
Second only to goggles...you may wish to consider a form of personal protection, as you tread the foggy/smoggy back allies of North Versailles, PA.
My favorite weekend project so far, was to pick up a $3.00 water pistol while checking out for groceries at the local store. First thing was a complete over-spray of flat black paint for a grounding. Metalic rub on paints from the local Hobbyshop really jump out with a black back ground. Then to the junk drawer for nuts, screws, rivets, knobs, etc.
If you wish to see the finished project, look on my page and photos. Im not saying it is a great build. But it was fun and an inexpensive, satisfying little experiment.
Be sure to post pictures as soon as it is finished, you have left me more than a little curious.
Whatever you do, you have my respect if you at least attempt something that actually functions. Metallic-painted water pistols are mere toys. I am on my first project as well, a simple steam engine manufactured from a tin can. I have not yet completed this, but it is a piece that, when finished, should actually function well and have a variety of uses.