I've started with the plaster work on the mountains.
I use a mix of WS moulds, home made latex moulds and alu foil.
The plaster is regular plaster of Paris.
I prefer to cast in situ. I wait until the plaster shows small wrinkles in the mould before placing it on the mountain.
I carve the surface with WS rock carving tools.
May need some more plaster in places.
I test painted the mountain...
I use regular acrylics and WS earth pigments.
Then burnt sienna.
And finally (?) gray stone pigment.
As it is supposed to look Colorado-ish, I hope this is the way to go.
It will lighten when dry.
Then some dry brushing.
I'm trying to match some photos I have of the Colorado mountains.
The color lightened a bit when it dried.
But the dry brushing went well.