Just happened to catch Wisconsin Gardener on PBS this morning. A man from Mt Horeb was showing how to make troughs out of styrofoam fish boxes that look like real rock. Now I have all kinds of ideas for putting mini hostas in them, and putting them at the back of the gardens to add height. Plus there is a fish/meat market a mile from my house. I will have to visit them and find out if they will give me some fish boxes.
Here is a link to instructions on how to create these troughs.
Here is the link to the transcripts of the Wisconsin Gardner episode.
Here is a forum where the they are discussing troughs and one of the pictures is one made of styrofoam.