Here we go.
My board is a 29" 1 x 4. 3/4" from the end I put a 20D nail in to hold my spool while I pull the material off.
2 1/2" down from that same end is where my finishing nails start to stagger the ends. 3/4" off one side, 5/8" from the other (2 1/2" apart) and spaced at 3/8". I have 10 sets, 11 or 12 wouldn't hurt.
7 1/2" down from that same end is my first measurement hole, for a 70" string. I have 30 holes, 1/2" apart for 1" string length increments (70" to 41").
26 3/8" down (measured from the same end) are my two end finishing nails, also 3/4" off one side and 5/8" off the other (2 1/2" apart).
Looks something like this.
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You will probably have to tinker a bit and adjust to make it work out just right for you.
Take lots of notes on everything. What colors you used, how many twists in the loops, where you started the loops, etc.. Just like shooting a bow, string building is about consistency. Do the same thing every time, then you will know how to adjust. There are plenty of mistakes to be made--don't waste time making the same ones over and over.
Keep in mind different materials have different characteristics, and you will likely have to adjust. I suggest sticking with one material until you get things figured out, then you might want to tinker with others.
Also keep in mind that using more or less strands will affect stretch/creep, and the length of the string can also come into play--how much varies with the type material you are using.
If I can help, just holler. I have a video, but I can give free advice via pm, phone, or e-mail.
Chad