Today i went to Hobbycraft and found a texture medium by DecoArt. It's meant to be mixed with acrylic paint to help with adding texture to paint work on canvas or other surfaces. I think it was a few £'s and looks like it will stretch to a few projects, so quite good value.
In the art department you can also find texture mediums in larger pots such as Windsor and Newton, Daler Rowney etc. The larger pots would be better if you had a large project to work on.
It's quite thick and slighly grainy, but much finer than sand.
I mixed some with Pva glue (white glue), because i found it improved the texture.
I just stippled it on with an old medium to firm paint brush and let dry.
Its dried well, but i have decided to give it a second coat to try and build up a more realistic stone texture. Tomorrow when fully dry i will start the paint work.
Because i have applied this to a polymer clay i thought it would scratch of easily but its sticking firm after several attempts to scratch it off. So looking good so far.
I also added a table top to the base from yesterday again with a star design. Hope it looks like i imagine when complete.