Here's the generator with a selection of 6mm, 10ish mm, 15mm, and 28mm models. I think it works best with the 6mm, but doesn't look bad with the others either. Though with the 28mm it'll be a power generator more than anything else. At 6mm it could a full on facility of some sort.
Yes, Lord Vader. I've reached the main power generators. The shield will be down in moments. You may start your landing.
(Thanks to Zachary for letting me borrow his WotC AT-AT)