Finding a nice piece of rock is everything you need to build a spectacular and useful terrain piece, just ready for the Storm of Magic Warhammer supplement
Important for breaking open landscape giving non-mounted troops some hope. Bear in mind that Roman legions were able to set up walls overnight and defeated the Gauls "with a pick not with a sword" »
To make small, round shapes out of cardboard use an office hole punch (available also with funny hole shapes nowadays) or better still a DIY punching tool used to make holes in leather belts and the like »