Decorative gourds can be dried in several ways and used for craft projects, bird houses, and as fall decorations; you just need to learn how. Drying them is not hard; they will mostly dry themselves, the timing is everything.
For best results, just let the gourds dry right on the vine if you grew them yourself. You don't need to place anything under them, just make sure they have good air circulation around them. Gourds that dry on the vine tend to be higher quality than those picked when immature and then dried. A gourd will dry even if it rains or freezes, although a freeze with kill the vine. Not to worry. Just leave the gourds until they are very light in weight and the seeds rattle inside them when shaken. Sometimes hard freezes will kill the seeds inside the gourd. If this matters to you, select a couple of gourds to dry inside in a cool dark place and wipe them down from time to time to prevent mold.
If you find mold on your gourds, wipe them down with a damp towel to remove the mold. Wear a mask or respirator while handling the moldy gourds and take care that the mold does not fly around.
Never scrape the outside of a gourd or cut a hole in it to hasten drying. This will damage the gourd and make it more likely to rot.
If you must dry your gourds off the vine, do not place them in small rooms such as garages or basements. This will promote mold. Instead, place them outdoors on top of pallets or something that will allow air to circulate around them. Any gourd that rots or has a soft shell after drying was too immature when picked and should be tossed. There is nothing you can do to restore it.