There is no limit to what you can create with this type of project.
You may simply want to add some large fake boulders in your garden design, make the facade for the waterfall and pond you have been dreaming of or a raised bed that doubles as a place to sit.
Once you know the basics of creating a rock, the method is the same no matter what the size of the project.
I've worked with concrete for garden projects for more than 10 years and I must say that for me it has been a very satisfying and addicting endeavor. One project leads to another!
Click here to go to the article, "How to Make Fake Rocks and Boulders" from eHow. You will also find links to other methods of making rocks, boulders, etc.