"Rock" troughs made out of styrofoam fish boxes

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.