First, the whatever-these-are called things you put before your guns - we call them 'baskets' which is quite close to what they are. Made of greenstuff, plasticine, sand and 9mm pistol cartridge shells.
Here you can inspect the bottom of one.
Cossack gun with baskets.
Comparison to a fig.
For 1/72 figures the Italeri Battlefield Accessory / French artillery / ACW Union artillery sets all have plastic versions of these.
In this box came one of the things I ordered from Model-Hobbies (on ebay) - now it's a ruined single-story building for WW2. It roughly matches 15mm size - for a large building. I see no trouble using it with 1/72s but I don't have anything more modern than WW1 painted in 1/72 besides a few tanks.
Scale comparison with a Zvezda StuG III.
The inside of the building was 'decorated' with cardboard slices and sugar to represent garbage.
The StuG can hide inside pretty well too.
This is a little stone well for 1/72 size battles. Either a simple prop or some sort of objective. I used the last bits of the static grass I had at home and left the next lot in the dorm - I will add some grass to the base later.
To scale with another Cossack.
In the meantime, I stripped the ACtA ECW gunners because the Revell 'matte varnish' (avoid at all costs) messed them up big. They'll be painted along with the other boxes on their way.
And a nice find, while we took the dog for a walk found this thrown into a ditch with my dad. A wooden chess table. Cleaned it up - the finish is scratched at some places but otherwise it's very nice. The letters were hand-carved and were very ugly at that, so I fixed them up and whitewashed them.