Herbs in coffee cans, hung with zip ties. Drill a hole in coffee cans & zip tie to railings! You could pretty much mount any container, like a box in this same way. bigger containers may require more zip ties.
GARDEN CRAFTS :: DIY Herb Drying Rack :: Picture frames + screen + chain = Herb, fruit, or veggie dryer. -- Or as a rack for drying painted papers, and other art projects. Platform feeder for birds. Imagination, go wild!