
The basics are you buy a mold, poor wet plaster into it and let dry, then you have super detailed building blocks for making a sturdy building of whatever you like.
creative tabletop monsters, creating realistic water fountains,
making colored windows, dead trees, tips for painting futuristic models and a lot of other tips and tricks then Bruce Hirst's site is the one to visit. I have to give an extra special notice though to his river sections, they're just amazing and create the most realistic water you could ever want to play on.
For the Anima Tactics players I have to recommend all the Gothic molds Hirst has for evoking the setting really well. Shard or other sci-fi game players could do really well with the Schematic Mold which I have my building pictures of above and to the right. Though I'm eager to see a Neo-Soviet player make good use of the Pipe Molds and create an impressive Soviet chemical factory.
Have I convinced you to have a look at his website yet?
This just about concludes the series I had intended on tabltop terrain. If you got anything else I should add, a different series idea, or whatever please leave a comment.