For my herb garden. This one doesn't show you how to do it but looks like a good project to start! It's also great for a tiny patio or yard. Looks like the pots might be too small though. so, build frame bigger according to pot size preferred.
Another version on rain gutter gardening. Want to grow a salad garden but have no room? Try gutters! Affix them to a fence, slope them for drainage, and voila! Of course,for this I'd need a backyard wider than a hallway.
These Stunning City Gardens Have Us Green With Envy