"Waste not, want not" isn't the official motto of the upcycling movement, but it almost certainly ought to be. Almost everyone, particularly parents, has old, Halloween costumes lying around - whether they're a bit tattered or the kids have just outgrown them. Either way, you can turn those old rags into new duds with needle and thread, ribbon, lace, embroidery, and whatever else tickles your fancy.
If the costumes you have are very old and tattered, and you have a bunch of them, cut out the most intact pieces of fabric and set them aside. Pin the pieces together until you have five or more feet in length from end to end. It's best to use a sewing machine if you can, but just stitch the fabric together in layers, bands, or whatever other pattern you choose using straight stitches. The result will be a beautiful, colorful, one-of-a-kind rag scarf that will have all your friends asking where you got it! (They might not believe you when you tell them that you made it yourself.)
If you have larger pieces of fabric or even mostly or entirely whole costumes, cut squares or rectangles and sew them together to create a poncho. Ponchos are incredibly easy, and many patterns can be found online (or you can wing it)! Alternatively, you can cut a skirt off a costume, cut it so that it resembles a large triangle, and once you seam it, add decorative features like beads, ribbons, or whatever else you choose. Either way, you will have a beautiful item that is uniquely your own, and if you have enough fabric, you can make a poncho to go with your upcycled rag scarf!
If you have large pieces of fabric that are mostly or entirely whole and go together color-wise, create a new skirt. An A-line skirt is the easiest; simply measure your waist and hips, and using those measurements cut the fabric in an A-shape to the desired length. Skirts are easy to fasten as well—you can use smaller strips of fabric to create a tie closure, you can sew in a zipper, or you can use buttons or snaps. You can also accentuate the skirt with other strips of fabric or ribbon in patterns of your choosing, creating a fun, unique, bohemian look.
If you're a dab hand at sewing, try an upcycled dress of those old Halloween costumes. This requires more measurements than just a skirt, and a good estimation of how much yardage you have to work with, but if you are working with flexible or stretchy fabrics this will make it much easier, so women’s Halloween costumes will probably work the best. Make sure to measure your bust, rib cage, waist and upper hips in addition to your hips and thighs—depending on the cut of dress you're going for—and fire up the sewing machine.
This is probably the easiest! The shape of a bag is easy to make, and you can piece one together out of small pieces of fabric or one large piece. Whether small or large, clutch or satchel, accent your bag with buttons, ribbon, smaller pieces of fabric, or anything else you like.
Upcycling can not only create unique and stylish items, but it can save you money and the hassle of shopping for what you want. No matter what you have kicking around from Halloweens of distant past, you can use them to create beautiful new items that express your unique style and taste.