I´m going to make a playable diorama and I think that i now have an idea to make it more real. To bring more realism to a diorama with hard ground everywhere and some hills in it, I was thinking about a "living" ground which is able to react to the things you are doing with your combat. I´ve tried some different sorts of material and come to the conclusion that cork is the best.
You can split it in many small peaces ( 4-5mm ) with a kitchen machine. You have to be carefull not to make the peaces too small - that will stop your combat when turning in one point.
If the peaces are big enough you can turn your combat untill it hits the ground like they do in reality. I´m going to make some areas with a deeper ground to fill it with splitted cork - the smaller the peaces of the cork the bigger the possibility that your combat will stop. So you can make different areas with different splitted cork to give a little risk to the game. If your combat is shooten in an area of big splitted cork - no problem but if you get shooten in an area with small splitted cork you are second winner.