Gourds are non-edible plants belonging to  the cucurbitacea family. There are basically 3 types of gourds, the ornamental, the utilitarian and the luffas. What makes gourds so unique  is not only their variety of shapes and sizes : they can be as big as drums or as little as mice, pear shaped, round or elongated,  but that once dry their shell becomes feather light yet  hard as wood.
This obviously explains why gourds have been  so popular  since pre-historic times. They must have spread easily too. Supposedly, a gourd full of seeds can float in the ocean for almost a year  remaining intact (this is called trans-oceanic  dispersion..)  
For thousands of years people all over the world have turned gourds into kitchen utensils,  tools, fishing floats, whistles, rattles and musical instruments of every kind. In Africa large gourds were even used as cradles and baths for babies and in Peru  people have carved gourds  with scenes of daily life reflecting history in minute detail. 
But back to the 21st century. Farmers' markets sometimes have an array of gourds on display and seeds of different varieties are available too. Whether you wish to make musical instruments, ornaments or  simply loofas for your bath, unblemished gourds must first be dried. Depending on size this can take anything from 1 to 6 months and it must be done in a warm, dry and well ventilated area, turning them often and always on the look out  for undesirable soft spots. In very hot, dry climates gourds can be left on the vine to dry in the sun.