You could go to a thrift store and purchase an old leather coat or two. Normally they are pretty cheap and the leather fairly thin and supple. It would also have some wear which might be a good effect for your steam punk look. I did that for the first leather corset I made. You could even incorporate buckles, pockets and straps from the existing coat for design accents. It sewed fine on my machine and was a much less expensive way to make one. With leather, anything that may get too thick for your machine, like the binding ,can be glued on. Hope this helps.