A few things to help if you haven't come across them on your own...
Best site going on hard core science based Pelusios info worldwide:
http://www.pelusios.com/index.php?option=com_frontpage&Itemid=1
The concept of using a molded plastic container for the structure and building upon it is a good one. Use of a storage/milk crate type container allows for better water flow/water quality. They are available in a multitude of sizes, sterilte produces some small enough to hold cd's and a variety in between. They tend to be a bit sturdier than standard storage totes, but more difficult to cut smoothly.
A dremmel with the right tool can cut fairly smoothly, but a heat gun, hot knife, or even a soldering iron produce the smoothest edges. Prior to using heat, I tried a variety of rasps and files but the heat option works the best, especially with some of the more brittle plastics.
I'm sorry I'm so inept with pictures and coordinating my camera and computer or I would post some for you.