Some history about this piece: When I was working for the GW US Studio back around 2004, we mass-produced a few resin pieces to send out to retail shops– Hobbit holes, Beastmen herdstones, a pallisade fort, and this 40K bunker.  I sculpted the master for this piece out of insulation foam, styrene card, Aves Apoxie Sculpt, and a few model bits.  The master was reproduced in resin, mounted on a piece of MDF and then the team painted and flocked them all.  I forget how many were made, but I was gifted one of the bare resin casts, which I held onto for all these years.

I painted the bunker and detailed the base with flock, static grass, and grass tufts.  You can see my assembly and painting process for the bunker in my hobby blog: https://robhawkinshobby.blogspot.com/2023/03/warhammer-40k-concrete-bunker.html

For size reference, the squares on the cutting mat are 1-inch in the photos, and you can see how a Space Marine (Primaris and First-born) stands at the windows.  The vehicle embankment fits the modern Rhino chassis (even with Predator sponsons).  *Figures and vehicle are shown for scale purposes only, and are not included.  Please message me if you have any questions.