I experimented with the "Tom Hall" approach to tying Turks head knots. This involves tying a base two bight Turks head and building it up to a 4 bight through an interweave process. As you can see I got severe twist in the knot. Once I work out the kinks and understand in such a way that I can teach it, I'll do some videos.
The fruits of my efforts were a couple jacks shown in these photos. In the following paragraph il explain how my design.
I started by cutting a coil spring to desired size with a hack saw. It was necessary to file the spring after cutting to remove any sharp edges and burrs that would wear the paracord. Next step, tie a monkeys fist around a steel ball bearing core (or lead balls as I did because the material density provides more weight for the same size). The two strands out of the monkeys fist are then fed through the center of the coil spring. This can be seen in this video I made on impact weapons. A lanyard knot is tied to prevent the two strands from pulling through the coil. If the coil diameter is too large, add a washer first. You want to work the knot tight to remove slack from the cords running through the spring - creating compression. No matter how tight you attempt to get this, it won't be enough.
The secret is to twist the monkeys fist one way, and the lanyard knot the other (clockwise vs. counter clockwise). This winds up the interior cords and creates stiffness and compression you want to avoid a "floppy" end. The problem is that as soon as you let go, they will untwist! I've experimented with a number of ways to prevent this. The best I've come up with so far is to create friction to resist the forces that want to unwind. I do this two ways. First, is to tie "support knots" that create a sort of pocket for the fist and lanyard knot. These also provide paracord on paracord friction. At the fist end, the support knot is a small turks head. At the other end, it is simply the long turks head I tied to form the handle wrap over the coil spring. Notice that the long turks head envelops the lanyard knot. The second way I created friction is to add a couple wraps of electricians friction tape to the paracord strands just below the monkeys fist knot and lanyard knot, before twisting. Once twisted, this tape mushes its way into the "support knots". After a bunch of whacks, it may still be necessary to twist it up.
Lastly, to use as my car keys and prevent ignition damage due to weight, I added a sliding turks head bead. You can see where this allows me to attach my keys, and provide some length such that I can rest the "ParaJack" on top of the steering wheel column - no weight hanging on the key.
Please visit my Paracordist Creations online store for unique self defense items for sale, and my Paracordist Creations LLC YouTube Channel for how to videos and make your own!