While puttering away at this terrain, I stumbled across a battle report in White Dwarf #456 which features this same Manufactorum line. The view from above, unlike the photos on GW’s website, finally showed me what was going on with the middle of each ruined floor: hazard stripes!
I laid down some 3mm Vallejo hobby tape and got to work.
After two thin coats of Averland Sunset, I peeled off the tape and drybrushed the entire floor with Celestra Grey (stripes included).
I didn’t worry too much about lining things up perfectly, or the difference between the “horizontal” and “vertical” portions (a natural consequence of my taping pattern). In the grim darkness of the far future, a Manufactorum would be a dreadful place — and an imperfect one.
When I started this terrain, I was listening to Dan Abnett’s Ravenor Returned, a portion of which takes place in an Administratum facility. Alongside the general impression of how miserable the place was, there was a bit where a character complains that his cart has a dodgy wheel — and his supervisor tells him that if he works hard for 10-12 years, he’ll merit a better cart.
That sequence colored my approach to this terrain, just as Brothers of the Snake (another excellent Abnett book) did with Squad Ariete. Those happy coincidences are one of the joys of listening to 40k books while I paint.