Of all the ways you can use to finish your braid for jewelry applications, a button and buttonhole is probably among the most elegant. It doesn't require glue and can be done with virtually any button so you don't have to worry about metal allergies. There's a wide world of colors, shapes, and materials in the world of buttons so you should have no problem finding the perfect button to go with your creation.
However, it's not entirely intuitive how to do it, so I'm going to show you my way. I start with making the buttonhole, using half of the cords for the main braid, then folding the buttonhole in half to start the braid, and end with the button. For the braid in this example, which is an 8 element kongo gumi/round braid, I am using Tex 210/0.5mm/"#18"/"regular" size C-Lon/S-Lon beading cord, size 8/0 Miyuki green/pink Picasso beads and green/pink Picasso drop beads, and a 5/8" metal button with shank. My disk for this example is a Dazzle-It 6 inch board from John Beads, and I used a one ounce fishing "lead" counterweight. Other tools are a pair of scissors, Fray Check, and a Beadsmith Thread Zap II.
Measuring your cord
First, figure out how long the cords you need for the braid will be before the button. As this is a bracelet, I need 4 40-inch cords. However, the buttonhole requires extra length. To determine that, wrap the cord you are going to use around the button four (4) times and add two inches. Then measure out the 40 inches you need for the braid from that point. Cut your cord at an angle and cut three more cords to match. Dip the ends in Fray Check to stiffen them for adding beads and allow to dry, about one minute.
You will then do a Maru Yatsu Gumi braid (4A in Jacqui Carey's Creative Kumihimo) long enough to wrap around the button, including the length of the shank. If you are unfamiliar with the Maru Yotsu Gumi, instructions can be found at Yoarra's Kumihimo Site. Note that site is in Dutch, and I suggest that you use the Google Chrome browser to translate it into English or another language. Once the braid is the length you need, undo the knot at the other end and bring those four cord ends up to the top of the disk and lay them out to start your kongo gumi/round braid. Add the beads for your braid. Work three or four rounds/repetitions without adding beads, in order to close up the buttonhole.
Once the beaded portion of your braid is the length you want, stop adding beads and work another 1/4" to 3/8" without adding any beads. This portion should be at least as long as the radius of your button, so when the button is laying flat against the braid it ends at the center of the button or just beyond. Remove any remaining beads from your cords. Now pick up two cords from opposite sides of the disk, pass the through the shank of the bead and tie in an overhand knot. Drop the cords you have used into the center of the disk so they are no longer in your way and repeat with the cords from the other axis--in this example I used the cords from slot 7/8 and 23/24, so the next pair of cords was 31/32 and 15/16. Repeat with the other pair of cords from the first axis and then the last pair of cords. Make sure that the knots are tight, but can still move around the shank. At this point, the button end of your braid should look like this:
Use your Thread Zap II to cut and seal the ends of the C-Lon/S-Lon. If you don't have a Thread Zap, use your scissors to trim the ends as close as you can and use a lighter to melt them.
And that's it! Your bracelet is now ready to wear.
Please feel free to ask questions or provide feedback on this tutorial. Let me know what did or didn't work for you.