Many similar ideas exist. I want to show you how to recycle 2l soda bottles and make a herb garden. The main idea here is that you water from the top and the excess water runs into the 'pot' below and so on. If you build one similar in size to mine you should be able to move it around or transport it easily. It also takes up very little space as it stands almost straight up.
Step 1: Hardware:
1)2l soda bottles.
2)Scrap wood, bamboo sticks, PVC or similar for frame.