To form the crater shape use a spackle (US) or polyfilla (UK), the latter being actually better as it is cellulose-based and does not shrink or warp while drying. Note that my projects that involve a lot of water-based spackling paste are usually constructed on a plywood base to prevent warping
Cover the whole thing with a PVA glue and sprinkle with fine sand:
Unpainted crater
When it is all dry, shake off excessive sand
Spray it all with a black paint
Drybrush it all with a grey paint
Glue some static grass to the base's rim
Blend the line between grass and sand with some black paint
The best tool for paint stripping in my book is... brake fluid. The one used in cars. You can buy it at any gas station and at many run-of-the-mill supermarkets. It is designed not to damage metal car parts or plastic pipes but also to prevent corrosion and remove impurities. »
Most fantasy and SF wargames are accused of being nothing more than glorified dice games. Whether this is true or not, dice are really the number one game pieces you will hold in your hand. They better be good then! The new dice from GW are great - if you handle them right, that is. »