I start out with 4 strands of rawhide about 50" - 60" long and 1/4" wide. Middle the strands and move a inch or two to one side to start the 4 plait loop. You could also do this part with a split braid.
sanjuanswivel_start loop by ss1442, on Flickr
I have the 4 plait wrapped around a 3/4" dowel and have started the 8 plait body of the honda here. Bruce Grant's book "Encyclopedia of Rawhide and Leather Braiding" has a good illustration of going from 4 to 8 somerwhere around page 200 (I'll get the page and plate numbers later).
sanjuanswivel_8 strand started by ss1442, on Flickr
Here I have the body of the honda plaited out to 6" or 7". You can go shorter or longer depending on how big you like your hondas. I have also pounded it some and ran it threw a rein rounder before I took this picture. I like running it threw the rounder because it streches it some and I want to get as much of the strech out of it before it gets used.
sanjuanswivel_ready 2 start neck by ss1442, on Flickr
Now I pull the strings threw the 4 plait loop.
sanjuanswivel_starting neck 1 by ss1442, on Flickr
That is Grant's "Encyclopedia of Rawhide and Leather Braiding" in the picture page 213 plate 82. It has a pretty good illustration of how to do the neck.
sanjuanswivel_starting neck 2 by ss1442, on Flickr
I have the neck part way done in this picture. It is a lot like doing a multi string nose button on a bosal.
sanjuanswivel_neck started by ss1442, on Flickr
I finish the neck by cutting 4 of the strings off and using the other 4 to tie the Spanish Ring knot. Then I use a hammer handle and some wood blocks to strech things out. I will leave it in the strecher to dry for a day or two longer if it is real humid out. Once I feel it is thoroughly dried out I will pull it out of the strecher but leave the dowel in place and boil it for about 90 seconds. That will make the rawhide harder so it is less likely to close up on your rope in use. Then it goes back in the strecher to dry back out again.
Once it is dry then I'll frequently coat it with polyurethane or spar varnish. Then it is time to put on the burner. I'll also wrap the area that will be under the burner with some wire to give it weight and to keep it from closing up.
sanjuanswivel_streching by ss1442, on Flickr