To cover the ugly crayola green septic lid!!! No way I'm paying $200 for a fake rock, I'll make one myself! :) How to Make Fake Rocks with Concrete: 9 Steps (with Pictures)
Yard and Garden ideas
How to Mix Faux Rocks
Solid Rock After One Year ~ How to make Artificial Rock and Boulders
How to make lightweight artificial rock
DIY How to Make Artificial Rocks, for my waterfall or to hide objects in the landscape ...
Crafts and DIY projects
HOW TO MAKE LIGHTWEIGHT, HOLLOW, ARTIFICIAL ROCKS. One way to make fake rock from concrete.
DIY - Outdoor
These are really more like boulders than artificial rocks. These things are HUGE! Not made of plastic so quite heavy though.
Artificial Rocks Covers
Neat video here on another way to make fake rocks. As fake landscaping rocks these look pretty good. They are not hollow though, so they can't be used as rock enclosures.
making artificial fake rock
How to Make Fake Rocks Using Expandable Spray Foam | eHow