Here is a step by step instruction video on how to turn a rubbermaid container into a "self watering" planter. It is not truly self watering but it is a sure fire way to ensure that your vegetables get a constant supply of moisture. Good potting soil and continuous moisture are the keys to successfully growing food in a container.  This wicking bed technique makes home grown food possible for any one with a small patio and a bit of enthusiasm. To be sure you can make a wicking bed from just about anything so long as you understand the principles in this video. If you are interested check out a post a made a few weeks back about a different approach to assembling a wicking bed.