Aight, let's get started.
Step 1: Ingredients
2. Marbles (2) > Really any type of round object of a similar size would work, rocks, balled up paper, etc.
3. Lighter, or Matches, or other Flame Source (don't hurt yourself...)
4. Sharp object for cutting the cord to length (again...don't hurt yourself...) I used a folding utility knife that takes razor blades that I got from (insert local name) hardware store.
Don't hurt yourself in the making of this, I am no way responsible for your mistakes. Also, the cost of materials and tools is very minimal in the case of this instructable, so I won't go wasting our time by listing it out.
Step 2: Tie the First Monkey Fist
1. As always, fuse the ends of the cord.
2. While holding one end of the cord, loop around your first and second finger (or if you're really cool, your monkey fist making stand...) three times. Make sure you actually have three strands on both the front and back of your hand, because if you don't, it might look funny.
3. After completing the three loops, you will make three more loops! This time, they will be perpendicular to your previous loops, and going around the outside, as shown. Pay attention to the transition from vertical to horizontal, as it may make the knot look funny when you tighten/finish. I would be more specific, but it is really hard to tie this and take pictures at the same time. So try it! If it doesn't end up looking good, redo it. In the course of this one instructable I tied the monkey fist at least 4 times to get it right.
4. Now transition (also watch your transition here) to vertical loops again, but this time it will be in the plane of your hand. This means through your fingers. Do one or two loops and go to next step.
5. Insert your core material (marble), and finish the three loops in this direction.
6. Congrats, you have tied the monkey fist! Now just to tighten it. This step is crucial to the aesthetics of the knot. The goal is to have only the one cord coming from the knot (the long excess part), and having the other beneath the wraps somewhere. To accomplish that, on your first round of tightening, leave the end sticking out of the perpendicular wraps so you know where it is later. This round, make everything tighter, but still very loose, as this is where you set up the shape of the knot. Try to make every cord have enough space to not be squished by its neighbors or other wraps. This should turn out rather cube shaped. Go to round two, where you tighten it snug up against your core material, again starting at the short end, and working the excess to the long end. The third time you can go ahead and pull the short end so it just disappears under the first wrap, and continue from there with the final tightening. Go Team!
If my directions confused you, or if you are more of a visual person like I am, check out this link, or google it.
Step 3: Tie the Second Monkey Fist
OK, this knot will be a little harder, depending on how much extra space you left. I found it was just barely doable with as much as I left, so if you left less...good luck ;-).
Basically, the instructions are exactly the same, except now you have to do it with a large ball on the end of the string. I (as you can see) looped the first set only twice around my forefinger and pinky to leave enough space to pass the monkey fist through for the last set. But when I got there, I didn't have enough length to make it through three times, so I had to move the slack from the first loops all the way to the end to have enough to make the last loops. You will have this issue too, it can't be helped easily.
After you finagle the monkey fist to complete the last three loops, you will need to go back to the first set and use the short end to go around again to complete the set of three. Then, it's just a *simple* matter of tightening the knot! If you ind the middle section too long, there are several in-line cord shortening knots such as the sheepshank you can employ to bring the length to a manageable level.
Enjoy your new bookmark!