Stonewalls made of oak

At work they made profiles for a customer in solid american oak and
the leftovers were garbage for some but not for me. :)
I looked at the U-shape and measured 25mm inside the gap and this
will fit perfectly for most of my figures.
The only figures that will not fit inside are my sotr-figures with
a base measuring 32mm i diameter.
The front and the back of my oak-profiles will be coated with 
cutouts that will look like stone-work when painted. I have not decided
yet if I will use polystyrene or cardboard but the most vivid choice
would be polystyrene. 
The U-profile measure 35mm in height and 45mm in depth and the
long pieces are 130mm in length.
I have not decided if I will add a base to make the profiles look more
wall-like but I think otherwise they will not look realistic.
I will probably add a base in soft MDF in a thickness of 22 or 30mm
and then the total height of the stone wall will measure 57 or 65mm.
I have also made a cut in some of the profiles (55 dgr) to make the
"stone-walls" more versatile. Finally I will make end-sections and
profiles with cutouts to symbolize rear entrances to the walls.

Here are also some pictures below to show how
I am going to make the stonework out of carved
ploystyrene.The pieces will be glued onto the
wooden profiles using pva.