I have played with this trialling several options, and usual ok with the results regardless of the materials
cork makes a great rock face, but matching and footing the bill can be jaw dropping
some real pebbles for extra detail
I moxed and matched with plastercast, then used the good stuff for closer ups
foam of different description (some more flammable than others, how do I know this? One techniques is to ‘fire’ it without setting fire and letting out toxic fumes - all windows open and a fire extinguisher close to hand - seriously
i like greys with a terracotta beige black and white mix, the earlier black white red yellow blue can achieve all colours in theory but I find the blue can be a pig,black for darker and shadows, white for highlights and fades blue yellow red any brown within reason,
plaster case draped over foam with enough horizontal for soil capture and grass growth and the odd shrub,
to date this form cliff face is my favourite, a knife ‘ saw for the vertical and horizontal cuts, b,ask into the crevices, sone of the beige is the foam poking through and a white highlight for salt bought out by the damp
sone deeper crevices for interest and possibly wildlife
cork tiles snapped
then weathered
this cheap packing foam had a rock like look
And taking advantage for other models..just because I can
real sand by the way
regardless find a nice reference picture,greys tend to blend nest, I like red sand stone but that would mean more pictures…grins