Thanks
Diorama is made of wood and plaster mostly, the rest is scratch-built (plastic tubes, electric wire, a Pringles tube box and a 6-pack egg box...).
Here are a few make-off pics of the "building".
The helmets are custom-made, I posted a little "how I made them" a few weeks ago
here (don't mind their old paint job on the post). Casting / carving / painting is approximately 4 hours each.
They look like
this on display, and I have one ready for Sgt Windrix's figure when it comes.