The Cucurbitaceae family contains more than 975 species of plants, including pumpkins, squash (zucchini, summer squash, etc.), cucumbers, watermelons, and gourds. These plants are known for their tendril-bearing vines and sprawling growth habits. 
Some species of gourd plants produce squash-like fruits that form a hard shell when dried. They are amazingly lightweight and durable.    
      "One of the earliest domesticated types of plants, subspecies of the bottle gourd, Lagenaria siceraria, have been discovered in archaeological sites dating from as early as 13,000 BC."

Gourds have been used throughout human history for water-carrying vessels, utensils, musical instruments, and decoration. 

The dried shell is woodlike and can be carved, painted, wood-burned, and this list goes on. Once sealed with natural wax, varnish, or clear coat, they can last indefinitely if protected from weather and water. My first gourd birdhouse has remained outside for years with limited wear.

They are a fun medium to work with artistically. I enjoy the functionality as well as the decorative aspects. I also appreciate the sustainable nature of working with something that can be grown in the garden. Growing, harvesting, and drying these beautiful plant forms is a joy.