Those AOL CDs are good for making hindering terrain. Just prime and paint them green, add some trees from a model railroad shop and it looks good. You can make water from plexiglass, just paint the bottom side, and it will have a depth effect. These terrain pieces will cost money, but you can slowly add them to your collection, especially if you already have the felt terrain system. The supplies and tools should be purchased as you need them.
Paintbrush varies with size thick brushes for big areas, tiny brushes for details.
I've only begun to scratch the surface of terrain building possibilities. I recommend starting with felt first, as it looks nice, is cheap, and is very portable. Hopefully, I've given you some ideas on where and how to begin. In time, you will find it easy to start new projects, especially once you've built up a set of tools. All Rights Reserved.