Dried bottle gourds are the natural choice when crafting a bird house. The size and shape attracts various birds, including the popular purple martin. Likewise, the gourds can be grown from seed in about five months.
Use sandpaper to smooth the exterior of the gourd and the inside edges of the entrance hole. To clean and sanitize the gourd, soak it in a solution made from one part bleach and nine parts water. Completely rinse the gourd in clean water and hang up to thoroughly dry.
Use exterior latex paint to decorate the outside of the bird house. Feel free to be creative, though a lighter color will help keep the house cooler in the heat of summer. Spray a coat of clear polyurethane on the outside of the house to protect the finish and seal the house.
Use a drill equipped with a 1/4" bit to drill three small drainage holes in the bottom of the gourd. Use the drill to add two additional holes at the top of the gourd to facilitate hanging.
Thread a length of leather lacing through the top two holes to form a hanging strap. Hang the bird house on a sturdy tree branch and enjoy.