Having undercoated my Ironclad Miniatures Victorian Science Fiction Tunnelling Machine, I painted the drill using Boltgun Metal.
This is a different process to the way I would usually paint something like this. Normally I would give the metal parts a black undercoat and then drybrush with Boltgun Metal. This time I am intending to use a black wash.
This is quite a difficult part to paint, as due to the design it is very easy to miss bits as you paint. I found rotating across the three dimensions certainly helped avoiding missing bits with the paint.