I'm looking into doing some designs for some laser cutting to produce some modular buildings for Necromunda / Imperial buildings. My thought being that with the way that everything is based off STC's there's a fair chance that lots of buildings in 40K ought to be built a lot like McDonalds restaurants can be - I remember a few years back watching one go up in a week on a new shopping park as I was driving to and from work each day. Most of the structure of the building was pre-built and turned up on the back of a lorry so it just got bolted together.
So, I figure that in the Imperium, if you want a building, you probably get the catalogue out and order your floor, your roof, and 4 walls. You probably get a choice of if you want a solid wall, or one with a hatchway cut into it, or window holes, etc. Like choosing kitchen cabinets and if you want doors with glass panels in, or solid wood, etc. Probably all stamped with similar but slightly different STC numbers.
So, onto the question. Assuming they were also stamped for a sort of 'manufacturers mark', (like bricks may have LBC marked on them), would that mark be an imperial aquila, or the mechanicum symbol?