If you need cord to finish off a knitted project such as a drawstring bag (or the perfect, period-accurate take-along project for when you're headed off to a Renaissance Faire), one option is to learn luceting. The technique for lucet cording dates back to the Viking and medieval periods, is fairly easy to learn (it may take a few cords before you get the tension down), and only requires a single tool, such as the one shown above, available from Stitch Diva Studios.
This video from Stitch Diva Studios will show you how to make a basic lucet cord. Once you are comfortable with the technique, it's possible to move on to adding beads to the cord, and even to making your own jewelry. Ziggy Rytka has written a book and a DVD on advanced luceting that are available from The Lucet Co.
When shopping for a lucet fork, you'll find it's possible to get styles ranging from the very simple and functional to quite decorative, such as the ones above, which are offered by Wooden Knitting.
This one from Grizzly Mountain Arts was too beautiful not to include, though it seems to be a one-of-a-kind piece made back in 2009 and that was sold on eBay, so if you want one like it you're probably out of luck unless you can either carve wood or know a woodcarver who can be talked or bribed into making you one. I do wonder whether a lucet fork needs a handle as it seems to me it would easiest and most comfortable to use if it had one, but there are plenty of both handless and handled lucet forks available for sale on the web, so it's plainly not absolutely necessary. It does look as though the handle is useful when it comes to making a very long cord, as the cord produced can be tidily wrapped around the handle.
This lucet fork is definitely not available for sale, being "a whalebone line-winder incised with the figure of a bird" Viking artifact from north Norway. Those Vikings certainly knew how to make cord.