These are the most common types of walls. Should you paint them with a textured paint? Use a texture paste? Or maybe just paint the surface using stippling?
An old way of modelling these kinds of walls was to use a home-made textured paint, ie. a standard acrylic paint mixed with sand. The effect was quite coarse and the walls looked like a sandpaper rather than a plasterwork.
You can compare this with other texturing methods I reviewed and decide which one suits you best for a given project.
For many years I have been using stippling
1. Paint the wall uniformly dark grey
2. Prepare a brush with light grey paint as if for drybrushing
3. Poke the wall gently with the brush until a texture is formed
This technique ruins normal brushes but you can either use an old, cheap brush or better get a special stippling brush.
But then I've head of the adventages of the texture paste
Texture paste is a kind of plaster/stucco that keeps texture of a tool used on it better then a normal one does. It is also easier to put as a thin film on any surface.
So I made an experiment. I built a new bunker and processed each of its four walls in a different way. I used a fine (ie. not coarse) texture paste. All walls were primed first with an enamel paint to prevent warping.
Note that stippling on the paste looks better then the one on flat undercoat as the brush bristles do not slide on it as much.
Judge the results for yourself. For my next plasterwork modelling project I am going to use the roller-texture-paste technique. And the sponge-texture-paste technique looks great for rocks and similar natural structures.
However I must say that I feel the stippling-over-flat-paste technique gives the most realistic effect in this scale.