Step 1: Create a Jig
Naturally, you will want heddles that are all the same size. Whether you are crafting 10 or 1000, they will not serve you well if their length is nearly the same throughout. To ensure consistency in your heddles, you should make a jig. This, as shown on Mirrix's tutorial, can be created with a simple piece of cardboard cut to size. I wanted something a little studier and permanent, so I followed their suggestion to create a jig using two finishing nails and a piece of wood. It is very important you use finishing nails. These nails do not have the large heads like other nails, as they are meant to be nearly invisible in finished projects. However, for us, the lack of top on these nails allows us to tighten our heddles and pull them off the jig with ease. If the nails had heads, our heddles would get all kinds of caught on the jig, rendering the jig itself a little useless.
Whether you use cardboard, a piece of wood, or nails hammered in to the side of your bookcase, you need to accurately measure the distance between your two points to be three and one eighth inches.
Step 2: Measure and Cut Pieces of String
For your heddles, you want to choose a fiber that does not have an excessive amount of elasticity and is strong and relatively thin. I used a 10/2 cotton for my heddles. From this fiber, cut pieces of string that are twelve inches (12") in length. Each piece will be one heddle, so cut the number of heddles you will need...and maybe some extra because you're making them anyway. Typically, you will need a heddle for every warp thread you intend.
Step 3: Tie a Loose Knot
Taking one piece of heddle material at a time, loop it in half around your jig. Secure the two ends together with a loose overhand knot.
Step 4: Tighten the Knot
It is important that you get your knot as close to the edge of your jig (whether a nail or the edge of a cardboard or thin wood piece) as you can. This ensures that your heddles all end up the same size. If you are careless with where your knots land, it will create small differences in your heddles that could lead to tensioning issues with your shedding device and inconsistencies in your shed itself. To create a consistently tight heddle on your jig, take a needle and place it in the circle created by your loose overhand knot. Then, using this needle, pull your knot as all the way to the end of your jig. Once the knot is resting where it should be, hold the needle in place and pull the tails of your knot tight.
Step 5: Trim the Ends
Trim the tails of your heddle so that they are within a quarter inch of your knot. (Long heddle tails could get tangled in your warps, so keep them tidy.) Pull or slide the heddle from the jig. Ta da! You have made a heddle! Repeat the process (Steps 3-5) for all the heddle material cut in Step 2.