i never have used Coffee grounds myself, mainly because i don`t drink real coffee.
Here is what i use along with a few well placed stones.
Bashed up Dog or Cat Litter, which is the self same clay used in green sand molding in industry.
It is also that used as a face pack beauty treatment,that ladies put wet upon their faces.
Yip! Cat Litter on their faces.
i have a very large bag of kiln dried fine silica sand , used in foundry's for C O 2 molds!
i also bought a very large bag of whiter sand used by Rodent Gerbils to help keep their fur clean.
Heaped sand upon wet p. v. a white glue, is very good for figure bases.
Or even plonked upon wet enamel paint will also do the base trick too.
Likewise even walls can be clad using this self same white glue method.
All three will be good for landscaping my diorama base too.
I buy on E Bay so it is quickly delivered to by front door,
and always the friendly delivery man from Appleyard Crescent Norwich,
will carry them into my home just where i need them most.
i am not able to lift and carry such heavy things myself.
Perks of his helpful occupation with a smile, gratuity: a good well earned tip! BB