Out of curiosity when I was a teenager (many, many, many moons ago, when the world was black'n'tan and steam was just about dying) I gathered some very small stone gravel from a beach, with the intention of putting it through Senior's old sand sieve, to extract the smallest pieces. The intention was to select small stones to build a stone wall on my (first) layout out of the natural materials.
As you will guess, it was an exceptionally tedious and lengthy process, and matching up the right-looking tiny little bits would have tried the patience of ten saints. However, while I never progressed further than the scale equivalent of a ten-foot-long length of wall, it looked well, and no artificial thing can come close. But it certainly knocked my next proposed projects straight on the head, which would have been to build a small stone cottage to put in a field at the corner of the layout. I'd still be at it......
I have been thinking more about that lately, perhaps to make a derelict stone gable wall of something like an old famine ruin in one of the fields near "Dugort Harbour". Maybe, if I've nothing better to do some winter.
There used to be some firm who made little plastic bricks and coping stones and stuff like that - is this still about, does anyone know?