I wouldn't want to complicate on things the reason why after learning about the main theme, I followed the very first thing that popped in my head. I decided to make a bonsai.
Step 1: WHAT YOU NEED
2) 18 and 16 gauge tie wire for the skeleton of the bonsai.
3) Spray paint. I used colors bronze and copper to make it look more steampunk.
4) Used electronics. Try to acquire gears. Gears are probably one of the vital part to make your artwork look more steampunky.
5) Newspaper for stuffing the skeleton.
6) Respirator mask for spray painting.
7) Other needed material such as phillips screwdriver, cutter, glue gun/stick, epoxy, duct tape.