I have JD Lindzen's book Tying It All Together, in one of the chapters he talks about how to make a small mokey fist. I use my scraps for that, anything shorter usually goes in the trash. You only need about 1.5 feet for the short side which is what I use my smallest scraps for.
He uses an overhand knot for the core, I like to use a diamond knot if I have enough cord becauseits more round, but the overhand will work imf your shorter on cord. In his video the yellow cord only takes three passes, thats what I use my scraps for, I will cut a fresh piece for the longer one unless I have some longer scraps. Then I tie a Snake knot or diamond knot with the tails, and loop one of the tails back through the hole to make a loop, put a keyring on there and sell them or give them away as gifts or a bonus with bracelet orders.
http://youtu.be/f1I-jxTdf4E