@ Walter: Thank you! Your sling is nice. It does have a replaceable end for the release cord or is there a change in the braiding pattern?
@Morphy: The usual loops in fistbraiding are made by
1. starting a braid, fold it over and continue with the doubled string count.
2. Starting the full braid, split in half, then recombine (as described by Jackinati).
3. Make a full braid for a long length, then sew it together to form a loop.
While all of these methods work, they have a couple drawbacks. Most are aesthetic though...
1. & 2. The look of the finger loop does not match the look of the rest of the retention cord. The loop has usually a different thickness or uses a different braiding method altogether. If you want the same pattern in the retention loop as in the retention cord you may have to work with doubled strings, which makes the retention cord utterly thick.
2. will produce a stub on the inside of your hand. I don't like that.
3. It is difficult to make the sewing strong, long lasting and unobtrusive at the same time. Also, where the braids are sewn together, a different pattern develops (which actually can look quite nice).
The method I posted in the previous picture is different as it is able to retain the pattern and thickness over the whole braid, including the fingerloop. It works by braiding both 24 strand braids into each other at a right angle (bottom crossing). So there's no "combining" (as mentioned by Jackinati) of the braids required. The same technique can also be used to cross a braid with itself to form a loop (top loop in the picture).
As mentioned, this retains the pattern and thickness over the whole braid. Also, it is strong as both braids, which are crossed, retain their internal structure and stabilize each other. There's no room for any wiggling.
Furthermore, the little stub will be on the outside of your hand, thus not interfering with your grip on the retention cord. Last, the whole unit of retention cord and retention loop looks neat and smooth. The loop does not form an individual visual entity but is part of the retention cord.
Last, I just like the technical challenge
Next step: Make an actual sling with this.