Ranger: I use a picture frame base with white styrofoam ( the kind with the big "cells" for mine ..... it is light , you can make various elevations easily ( just glue on extra pieces and sand it ) ,cheap, and best of all , as opposed to clay very light ! The only drawback , you have to watch out when working wit some solvents , as they sometimes tend to melt it ,,, ie clear epoxy or spray adhesives. I then top it with a thin layer of plaster of paris here is a latest work in progress ( with hilly terrain I am working on now ))http://us.f1f.yahoofs.com/bc/68ab916d/bc/pantherD1-02-04/diounfin2.jpg?bfO9pAABlwujJoYM may have to cut and paste url ,,,,, note the melting of styro from epoxy This in unfinished BTW , much more to do here