UPDATE: 2018-01-25. ‘The Long Haul,’ in LEGO.
I received a question about the underside of the Grantmasters LEGO Refinery and received a response from him about it:
The bulbous parts for the underside of the refinery were 4×4 gray circular dome plates originally but I have long since used them in other projects unfortunately. They didn’t match the profile of the refinery exactly but it was close enough for the scale. Currently the underside doesn’t have much left in the way of detail/ greeble etc as I needed to re-use those pieces too. It still looks good from the top though.