Many years ago (back in the early 90's?), I played in a Dwarves vs. the Drow, BattleSystem game, at a convention. I've always wanted to re-create that bridge
And now I am.
Here is a link to my Blog, which has the details, thus far: link. While it is not complete, you can get a very good idea of what the finished product will look like.
I used cardboard tubes as armatures, with gross surface texture created by Hot Glue, and minor surface texture achieved with PVA Glue, and sand. The medium used, is not important. Painters choose the medium they prefer, such as watercolors, acrylics, oils, or even pastels. Terrain-making is also an art form -- use whatever medium you enjoy. Hopefully this posting will inspire others to get creative. Happy gaming! Cheers!