Hi Benno...
First I use a Styrodur Foam Plate as Base!
Then cut of a second Plate as a Hill and glue it on the First!
The Earth is a mixture of Molto Holz-Reparatur-Spachtel and Bird-Sand and brown Dispersion Paint!
I mix these components then with a spatula.
This mash is applied on the Styrodur, make Tracks and Craters and after light hard the mash, I brush it dry!
You have enough Time to change it, till you like
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Then glue the figures on it and raise the grass!
Ready!
The mass does not contort, there originate no tears on the surface and it is much lighter than gips!
Perfect for every Diorama use, if you change, for example, the ground Colour or the Sand...