OK,
Secrets revealed.
Here is the culprit.



I started by chipping a small ding in the corner of the wall. I tried to save the pieces chipped off but they were too microscopic so I made some plaster bits and stuck them on the ends of narrow gauge brass rod. I drilled small holes in the gauged area and stuck the brass rod pieces in. I then painted the parts very carefully to blend into the wall color but kept them light,for contrast.
Stretched pieces of cotton from a swab were then glued to the area of the brass rod between and betwixt the plaster bits and the wall. That part took a bit of trail and error.
Much harder to see are the blobs of mud from 20mm strikes on the ground. I have to work on that technique some more.


HTH bubba,
No tricks,just cheap, low-tech stuff,as usual from this old grunt.
J