What ho!
Another Sudan based enquiry (yes, it's my new obsession).
Zeriba fences, as used in battles, any suggestions?
Rubberised horsehair - Stick to a base and dry brush - Bob's your uncle
Quick example I know 28mm and round but hopefully gives idea:
(https://i.postimg.cc/9fPdSrqN/zariba.jpg)
I was going to suggest green scouring pads cut to size, glued to a suitable MDF base and painted in various shades of beige and brown.
However, the horsehair works too.