This view shows the way Craig has ran dados to slide the expanded metal shelves in and the board that protects the front of the watering box.

You can also see a close up view of how the jar and the pyrex tray fit together. It doesn't have to be a Pyrex brand tray. Any brand will work.

It is getting harder and harder to find glass jars, so Craig is very careful not to break them. There are many plastic jugs on the market today that would probably work as well. They don't fit right in the system he has designed, but they would with some slight modifications.