[SteveBerenyi]

here is the trick:

get plaster of paris, a can of krylon clear coat, a rubber ball, and some paint.

put a blob of plaster in the middle of your terrain piece. put the ball on top and roll it around with your hand.

let it dry thouroughly, then paint it. SEAL IT 3X with the clear coat!!!! that is what makes it usable as a terrain piece.