I took the third theme round quite literally and built a few elements of defensive terrain for a Chain of Command Espana. I've been dipping in and out of building and painting these for weeks. The support option lists call for the usual: entrenchments for teams (~6 men or a support weapon) and 6" sections of barbed wire. All of these are scratch built from supplies I had in stock.
The entrenchments are based on some 2mm foamed PVC, cut into gentle curves. The earth bank was built up with foam board and filler, and balsa wood supports built at the back. The sandbags are plastics from Rendra I thought these were a bit steep at £8 for two sprues, but this is perhaps half or 2/3rds of one so you get quite a bit from them. The groundwork done in my usual way - sand over PVA glue.
I built two barbed wire sections on Warbases terrain bases, with holes drilled and some bamboo cocktail sticks glued in. The wire is from Antenociti's workshop, I find a bit of black wash and iron oxide powder brings it up a treat. I would have liked twice as many of these but am out of the bases? having made some in 15mm using the same method. I used two layers of wire in a fairly historically accurate pattern.