A project I've wanted to take on for a while now is to build Zone Mortalis table. I looked into a number of different options for how best to go about it, in the end I stumbled upon a particularly awesome set of products over at www.hirstarts.com. They sell molds of modular terrain components you then cast copies of and use like legos to build your own terrain.
A week later and my 11 molds arrived. The rubber is really high quality, good tensile strength and very durable. It also came with some great tips on maintenance and storage which will be quite helpful for newbies.