Last night I made up the cooker hood ductwork, which has turned out very well I think. It's not shiny, it looks industrial, a little bit rough - which is exactly the look I wanted:

I even profiled the bottom of the plenum box to fit the curved glass, but I havent taken a photo of that. It was only to get the box to sit flush with the wall, not for any aesthetic purposes, although it does look quite good now I've done it.

Here's the loft side of it, and you can also see the duct popping up from the bathroom extract fan. These will be completed by cutting holes through the wall on the right, and I have some stainless vents to go to the outside world: