All you need are a few - pavers, landscape-block adhesive, and a little time. Wait 24 hours for everything to cure and you're ready to move your new planters into place and fill them with dirt and greenery.
Really great idea for saving water! Rain water is better to water flower beds with, so this is an awesome idea. I saw this on a show not too long ago. You can hook up your hose and water your garden too.